I’m trying to rank for a particular keyword in the serps & I’m
going to use document sharing Sites like docstoc.
When I create a pdf document whats the best keyword density
and do I need to make the keyword phrase hyperlinks, put quotes
around it or just leave it like a regular phrase in the pdf.
In order to rank you should be forgetting about things like keyword density and write content that’s useful.
I’d agree with what’s been said, just concern yourself with the quality and people will view it. In this case, having a well designed and illustrated pdf might make it pop more on public sharing sites such as these.
Also, if you have a website, you should always start there. I’m a fan of having an HTML page for all PDFs I plan on showing - some people like the page, some like the PDF, it’s good user experience.