On the MacBook Pro 14" when connecting to RDP the desktop displayed cuts off about 20-30 pixels at top and bottom. The MacBook display is set to "Default for this Screen" btw This is a great app...
I stumbled on the solution. Edit the RDP settings for the machine itself, click on the display tab and check the two boxes for optimize to retina, and update resolution on change. That fills the screen nicely without clipping. Hope it helps! Thanks