I based myself on written accounts. I thought (ccould be wrong) the city of Köln was part of the kingdom. Since I didn't want to mess around with the German duchies too much, I simply added the entire duchy. I'll look into this, and maybe fix it
Also: I re-uploaded the file. Something must have been wrong with the previous upload. If there still are problems, let me know!
Here's a map for reference: http://upload.wikimedia.org/wikipedia/commons/4/42/Partage_de_l%27Empire_carolingien_au_Trait%C3%A9_de_Verdun_en_843.JPG
The biggest problem is that it really runs along the Rhine, but the provinces (and cities, like Koln) are sometimes on the river. Looking at it again, I think it's okay to inclue Kleves, but Munster should be left out. Also, I was wrong about Mainz; it looks like it was carved out for Germany after all. I may have included it in my mod for CK1 just to give Lorraine somewhere to expand.
So, consensus? Remove Munster?
Bruce
Edit: The new file looks identical to me?