Printing to PDF for most ERD's is pretty difficult to do unless you can finagle some pretty large page sizes for your ERD Images. You can export your images as JPGs, but you don't get some of the cool features of being able to see definitions and details.

And to Steve's point, it is quite a bit more convenient to give someone one ER Studio file and let them view it, but licensing for viewers can be a pain. I can definitely understand that point of view. We just found that publishing the HTML Reports was generally a workable option for our teams. 🙂