The Report Viewer uses an existing Report instance to create an export output (in your case - PDF). It is not designed to load or print existing files, so there is no way to fulfill your scenario.
Reading about your requirements, you would probably need to use 3rd party software - like the Adobe PDF browser plugin
or Foxit SDK
that is designed for displaying and processing PDF files and would be more suitable to your needs.
Have you tried the new visualization options in Telerik Reporting Q2 2013? You can get them from your account.