Privacy Pane wont let me add a preference pane to control my computer
This is a known bug in the latest OS X Yosemite. You can’t select or drag prefPane extension file from the Finder window dialog.

When you’re prompted with the same screen, press Command+Shift+G and enter the path to the packaged application at: 

~/Library/PreferencePanes/FunctionFlip.prefPane/Contents/Resources/

Check out the gif to see how it works.