If you’ve ever been given a pdf file that you want to edit, or a pdf form that you need to complete and return electronically, you’ll realise it’s not obvious how to edit a pdf file. The good news is that the OSX built in pdf reader app – ‘preview’ – can edit pdf files. You can’t move around or change what’s already in the pdf document, but you can add text and graphics. Here’s how. 
If you double click on any pdf file in OSX it will open in an application called preview. You can read the pdf and scroll around etc.

Go up to the View menu and select the menu item called ‘Show Annotations Toolbar. This will give you a toolbar along the bottom of your preview window to help you edit the pdf file.

After you select  the ‘View: Show Annotations Toolbar’ menu you will see a toolbar across the bottom of the preview window that looks like this:

These buttons will allow you to edit the pdf file. The left three buttons make an arrow, a circle or a rectangle. The fourth button along allows you to add text to the pdf.

If you click on the text box button – the 4th button across,  you can then go up to your document and add in a text box like this:

If you click on the text button you can add a text box to the pdf document like this.

This is a very easy way to fill in pdf files that are forms.

If you highlight the newly added text you can change the font by pressing Apple-T and the font window will appear.

You can’t delete  what’s already in a document, but you can draw a rectangle over it to hide it and type something new over the top.

You can cover over existing text using a rectangle with a white border like this.

You’ll notice you can’t change the rectangle color from being black, but you can put a very fat white border around it so it looks like a white rectangle!

If you want to totally change the images and text on an existing pdf file you will need an application like Adobe Illustrator that can actually edit the content of pdf files, but if you only want to make small changes the built in preview app will do the job!

Depending on what program you used to create a PDF, the file size of your PDF file can be quite large. If you combine two or three PDF files together using preview, you can also end up with a bloated PDF file.  The best way to reduce PDF file size is with Acrobat professional, which can do all sorts of magic on PDF files. But here is a free  way to make a PDF file smaller. Firstly, open the PDF file in ColorSync utility. The ColorSync utility is found in the utility folder of the applications folder of your computer. If you don’t know how to find that, simply right click ( or option click if you have a one button mouse) on the PDF file, and select from the menu open with,  ColorSync utility.

This will open your PDF file in colour sync utility. Go down to the bottom of the window to the drop-down menu on the left that says ‘Filters’  and select ‘reduce File Size’.  then click the button in the bottom right  of the window that says apply.

Select the filter that says reduce file size

This will go through and re-compress the images in your PDF to make the file size smaller.  Don’t forget to save the file after you’re finished,  you may want to use ‘save as’  so that you still keep the original copy of your PDF file.

Combining pdf documents on an Apple computer is easy. Leopard and Snow Leopard (the latest versions of Macintosh OSX that come on your computer) have the ability to move pdf pages within a pdf file around and even merge two different pdf documents together. It’s built right in to OS X for free –  you don’t need a third party program to do it!

To join two or more pdf files together using Preview (the standard pdf viewer in OS X) simply open the pdf file in preview, open the thumbnail view (Shift-⌘-D), and then drag a second pdf file ON TOP OF an existing page thumbnail. (It must be on top of the thumbnail, see the pictures below). The two documents will merge into one. Then save the new combined file. Read on for step-by-step instructions.

SUMMARY: To combine two seperate PDF files into one document you need to drag the new pdf ON TOP OF an existing  thumbnail and it will merge the two together. If you drag it into the sidebar but not on top of an existing page the new file will be added as an external link – not merged into the original pdf document. See these two pictures below to visualise the difference.

Drag the new pdf file under the existing one and it will insert a thumbnail that links to the second pdf but they are not merged.

Drag the new pdf file on top of the existing one and it will merge into it - creating one pdf.

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The blue line that appears underneath the original pdf lets you know the files are NOT being combined. Move the pdf on top of the other pdf so that the blue line disappears.

Here’s how to do it step by step.

1. Firstly, open one of the pdf files in Preview. Preview is the default application that a pdf will open into so if you just double click on the pdf file it will open in Preview.

2. Now go to the menu at the top of the screen called ‘View’ and click on ‘Sidebar’ (or  ‘Show Sidebar’ if you have Snow Leopard). Alternatively, press Shift-Command-D to show the thumbnails. This will make a sidebar appear on the right side of the window with thumbnails of all the pdf pages in it. (See these pictures below).

In Leopard select 'Sidebar'

In Snow Leopard and newer versions of Preview select 'Sidebar' then 'Show Sidebar'

3. You can now drag the second pdf file (from a folder or from your desktop) into this sidebar window, and it will be added to your pdf document as an additional page.

Drag the new pdf from the desktop onto an existing thumbnail.

To merge the two files you need to drag the new pdf ON TOP OF an existing  thumbnail. If you drag it into the sidebar but not on top of an existing page the new file will be added as an external link – not merged into the original pdf document. See these two pictures below.

Drag the new pdf file under the existing one and it will open but not merge.

Drag the new pdf file on top of the existing one and it will merge.

In some older versions of Preview, if you drag the second file on top of an existing page in the sidebar, it will appear as a red box to show you it will be merged, or as a red line to show you it will not be merged.  In the latest version of preview, the red box does not appear, but the same principle applies – drag it on top of the existing thumbnail to merge the two documents.

You can now save it – use ‘save as’ to save a new document with the merged fles, or you can use use ‘save’ to save over the existing document, adding the new pages to it.

No – you can’t reduce  the file size of the new PDF document –  you can’t get everything for free! To do this you Adobe Acrobat Professional.

Like this article ? Click here to for how to make a pdf booklet. Also here for how to reduce the file size of a pdf.