This is a bit of an odd one, so let me describe the situation.
I have a MacBook pro with Retina Display (2880x1800 native)
I have installed Parallels 8.0.18483 (current as of posting this msg)
I have Windows 7 Professional with all current patches installed into a Parallels VM.
I used to have a MacBook pro with a normal display (1440x900) and when I connected to the RDS server, and started up an application, everything looked fine in terms of scaling, fonts, etc.
I have just upgraded to the Retina Display, and now when I login to the RDS server, the web components of the application icons look fine, but when I launch an application, it comes up extremely tiny and almost impossible to read.
Other than reducing the resolution of the MacBookPro before starting the RDS session, is there some setting I can change to make the applications scale properly?