Is this a set list of PDFs, or do you want to arbitrarily be able to open any PDF? And if it's any PDF, what's wrong with Command-O, which will open the selected PDF in Preview?
I guess I'm having trouble understanding what you're trying to accomplish with this macro—can you explain in a bit more detail?
When you say "specific pdfs," what do you mean? If you just mean PDFs that you spot while browsing around finder, then I don't see the need for a macro—a double-click, or Command-O after selecting a file, will open it. But those are standard Mac actions known by everyone, so I can't believe that's what you're wanting to do.
Why is a macro required? That's the part of this request we're all struggling to understand. I assume it's related to "specific pdfs," but you haven't explained what that means.