Você tentou a opção de 2 dedos para clicar com o botão direito nas configurações do Trackpad? Esse é o método 'aceito' do MS RDC.
Em Technet - link
How do I enable secondary right-click on your Mac?
In order to make use of the right-click inside an open session you have three options: Standard PC two button USB mouse
Apple Magic Mouse: To enable right-click, clickSystem Preferences in the dock, click Mouse, and then enable Secondary click.
Apple Magic Trackpad or MacBook Trackpad: To enable right-click, click System Preferences in the dock, click Mouse, and then enable Secondary click.