Originally Posted by kovidgoyal
You are right that its is a difficult problem converting an arbitrary LaTeX file into a PDF of a given size with the correct fonts. I've had some success with just inserting a \geometry command and changing font sizes in the preamble, which should be easy to script...though I suspect this approach wont scale well to all papers, especially older ones that dont use best practices.
We do both in the preamble too but anyone could change the fontsize using the fontsize command for example.
Still, I do believe that it'll be much easier to convert a file for the reader using our interface than trying to change everything on your own, we just need a whole lot of thinking on what will be needer for scientific papers and the best way to get them on the website.
I might be working on this matter with people from INRIA, they seemed interested in using the reader instead of killing trees everyday for their daily reading sessions.