Here's the problem. There is absolutely no standardization in page size on smartphones. There is no standardization on what PDF reader your readers will use. You probably need to do it by testing what font sizes/fonts look best on target phones you expect your users will use.
Thank you Steve. I am currently experimenting - designing, downloading and testing with smartphone. Looks like that's the only way to go. When I get that right, I can use my first magazine as a template, and build from there.
I like the reading mode of Adobe Acrobat. Will spent a lot of time this holidays on my design. Starting from scratch with no template looks the only way to go, thanks again.