Juan,
Thank you for contacting us about pdfreaders.org.
On Wednesday 01 December 2010 15:00:10 Juan Ramón González González wrote:
i find your site to be a great initiative to spread the use of free and open source alternatives to Adobe Reader for reading PDF files.
We're delighted that you find the website useful!
But i think that what for me is the best alternative for Mac OS X is missing on your list. I am referring to the Skim reader available at sourceforge
Unfortunately Skim is not entirely Free Software. Only the front-end of Skim is available under a Free license, the back-end (its rendering engine), which does most of the work of reading PDF files, is under a separate, proprietary license.
Statements on sourceforge about Skim's licensing only refer to the parts which are Free Software; sourceforge does not host all parts of Skim that are required to make it work, including those parts which are proprietary.
This is why we do not list Skim on pdfreaders.org, although we have been aware of it for some time.
Many Thanks for your enquiry,
Sam.