Question: Does any know how to get the RDP version Windows is running with?

Answer: 
Or you could Right click on the window and select About
![enter image description here](https://i.stack.imgur.com/CvjyF.png)
Windows RDP uses the executable mstsc.exe located in c:\windows\system32

Simply right click on this file, and go to properties, then click the version tab.

hope this helps.