Telerik Reporting produces standard 1.6 version PDF file - more info in Design
Considerations for PDF Rendering. Anyway decided to test this, so I exported the ReportBook demo (http://demos.telerik.com/reporting/report-book/demo.aspx) to PDF, uploaded it to a host and it is opened just fine from google docs (http://docs.google.com/viewer?url=http%3A%2F%2Fdl.dropbox.com%2Fu%2F4210319%2FReportBook.pdf). So there must be something else wrong on your end - i.e. permissions from the host, check whether it can be opened directly like so http://dl.dropbox.com/u/4210319/ReportBook.pdf. Or if you're not linking directly to pdf but to a page that serves the file - check whether this logic works correctly and can be handled by google docs in a first place i.e. with generic pdf not generated by Telerik.