And if you want yet another option, there is Skim which is free and 
open-source. Skim has quite a few capabilities as well as PDF markup, but is a 
bit harder to use than the other tools. Here is an article describing its use:

http://doctoralschool.wordpress.com/2011/07/15/skim-scrivener-research/

Just thought I would give you the option.

Regards,
Carlo

On 27/06/2012, at 9:42 , Severin Crisp wrote:

> I regularly use PDFpen.  It works just fine for me.  
> Severin Crisp
> 
> On 27/06/2012, at 9:20 AM, Curtis Peter wrote:
> 
>> Hi
>> Can someone recommend a simple program to allow me to write to/on a PDF? 
>> Regards
>> Peter
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