Filezilla on Mac: SFTP with passwordless authentication?
Solution 1:
You can now use FileZilla -> Preferences -> Connection -> SFTP which will allow you to import your private key.
Solution 2:
Recent versions of OSX have the ssh-agent built-in and there is no need to start it separately.
In my case I simply had to change the logon type to "interactive" in the sites settings in FileZilla and choose SFTP as the protocol.
FileZilla apparently talks with the ssh-agent and handles the authentication. This is better than importing the key to FileZilla, since this way you can keep the file password protected.