I found these instructions on
MobileRead Wiki page:
Aside: Here's a comprehensive E-Book Reader Matrix on
the MobileRead Wiki.
Taking a look at
the MobileRead Wiki on ebook stores, I see that majority of ebook stores they list (and they list a lot) are noted as having PDFs available and several are listed as having PDF only.
There is a huge list of readers here on
the MobileRead wiki, so if any of the ones I've listed above don't suit you, you can probably find something there.
Not exact matches
See the
mobileread e-production
wiki for better information.