FileZilla on Mac OS X can't open .ssh directory to get my keyfile
Solution 1:
In any Open or Save dialog in OS X, simply press Shift-Command-Period to display hidden files and folders.
http://www.macworld.com/article/142884/2009/09/106seehidden.html
Solution 2:
Alternatively to displaying hidden files/folder, you may find it easier to navigate there directly.
CMD+Shift+G will display a dialogue box to enter the path. Then enter ~/.ssh, and you're in.
If you enter the path to a file in an Open/Save window and press enter, it will choose that file to be opened/saved.