If you want to make rsync-over-ssh to use specific 'ssh' options like, using a different identity key than the default one, you can use the '-e' rsync argument to pass options to the ssh command.
Example above :]
# make rsync to use '/root/.ssh/non-bugged-id_rsa' to authenticate against the foreign host#
rsync -avuz-e'ssh -i /root/.ssh/non-bugged-id_rsa' remoteUser@remoteHost:/path /backup/path