By design, Remote Desktop Connection, only has the option to “Use all my monitors for the remote session”.
But lets say you have 3 monitors and you would like to use only 2 for Remote Desktop and leave the other for local use.
In order to do this, you’ll have to manually edit your C:\Users\YOURUSERID\Documents\Default.rdp file with a text editor. Notepad will be fine.
Before you start editing, open command prompt (win+r) and run this command:
You will get the following popup:
Now you can edit your Default.rdp and append the following lines at the end of the file:
span monitors:i:1 use multimon:i:1 selectedmonitors:s:4,3
Remember to replace monitor numbers (in my case it’s 4,3) with your configuration, save and enjoy!