You can use a simple Terminal edit to disable Safari from natively browsing PDF files, so that you can use Acrobat or any other PDF viewer that you might have available.Quit Safari
Run Terminal, and type the following:
defaults write com.apple.Safari WebKitOmitPDFSupport -bool YES
Restart Safari
If you want to revert this process, you can quit Safari, run Terminal and type the same command with the value "NO" instead of "YES".
