RMS Rectangle Map

I don’t really know much about RMS. Need to generate a rectangle map with the borders so I can import it to the scenario editor. I tried looking into the randmap for black forest since it generates a square map but the files are encrypted and can’t really configure it.
Any tips and advice are appreciated.

You can check here how to make rectangle maps, Araucania like.
https://web.archive.org/web/20100421112530/http://hyenastudios.mugamo.com/aoe3rmstutorial.htm#I2https://web.archive.org/web/20100421112530/http://hyenastudios.mugamo.com/aoe3rmstutorial.htm#I2