Use Retina resolution in Microsoft Remote Desktop
Click the Pencil [edit] Icon at the top of the main RDC window &amp; set a higher remote screen resolution.
'Native' might be as good as it will let you have.

Scale content might not be good on a Retina screen - but it might appear quite small without it checked.



I have a feeling, which I'm unable to test, that it may be related to the maximum resolution of the remote machine's graphics, not the local - as you can always set the local machine to scale the remote's resolution to fit the local screen - e.g. for dual monitor remote, single monitor local.