Create a Batch file (make a text file with notepad, then change the extension from .txt to .bat) You have to show extensions for file names to do this, either by editing the name or changing it in explorer. If warned about changing the extension, just say okay, that's what you intended anyways.
Copy/Paste the following lines of text:
==========================================
cd c:\
cd Program Files (x86)\Steam\steamapps\common\Red Orchestra 2\Binaries\Win64
rogame brewcontent TE-MyMapName
pause
==========================================
Replace "TE-MyMapName" with your map's name, "RSTE-Kawabunga" for example.
I keep my batch file on the desktop. After closing the SDK, then brew my map using the batch file, of course after changing the name of the map to whatever I'm working on at the time. Because the editor is closed, brew times are less, and more of your computer's resources are available.
Two command windows will appear during the process. That's normal.
After completing, a new map file will appear in the Published directory. If a map with the selected name is already there when you start, it will spoil the brew and possibly corrupt the unpublished file.