I had to do the same thing so I created a read only attribute. (Rather than hard code it, it allows me to put it on the products/categories that I want, instead of EVERY product page.)
In the options value (for a read only) I added this:
Code:
<a href="javascript:void(0)" onclick="window.open('yourfile.pdf','name','width=250,height=800,scrollbars=yes')">Name of the File to Appear on the Page</a>
If you choose to do a read only attribute, you will probably have to get into your database and change the value (default is 64 characters). I also went in and changed the wording instead of "Please choose."
Hopefully that helps!