This is absolutely not a common behaviour !
Check if the file has the obvious PDF extension (the name should end with .pdf). Although the extension might not be visible on a Mac, it defines the nature of the file, so the Mac knows which available applications could be used to open it.

Note: simply hitting the space-bar with the PDF file selected in the Finder will display the QuickView window for this file. So no application required !

Without being able to take a closer look at the file, I can't give a diagnose or advice.

Oorspronkelijk geplaatst op Quora: Why can't my recipient open my PDF file on his Mac if it's no problem for me to open the file and view it?"