Possible Duplicate:
How can I highlight PDFs?
I am using Ubuntu 12.04. I collaborate with others on academic papers and they frequently send PDF versions of the document we are working on with comments and annotations to me. In this case they placed comments using a PDF editing software on Mac. I can view their comments using Okular -- but when I insert any comment or annotations using Okular on the PDF they are not able to see it.
To clarify, the PDF editing software itself does not have to be cross platform, as long as the result can be saved and viewed on other platforms. How can I add comments and annotations to PDF file so they are viewable on other platforms and popular PDF viewers. I am looking for a reliable solution. Missing annotations can result in serious miscommunication when collaborating with others remotely.
ps: this is not a duplicate of this post on viewing comments since I am looking for a solution that let me reliably annotate and comment on PDF files and email them to others for viewing.