Ruthmann/Roetman/Roeteman

Greetings,

I am new on this list.
I am looking for an ancestor of mine, named Johannis Ruthmann. The only details I know are :
born round 1754, do not know where, married at 1787 in Sommelsdijk, the Netherlands. Since then he was named Roetman. His marriagecertificate tells that the was from Millingen near Rees (so not born there) . His proffesion was a baker. Uptill now, I surched in many archives in Holland without any result.

Is there anyone who can give me perhaps more information about Johannis Ruthmann, or gives me information about German genealogy sites?

I also have other ancesters from different Roetman familytrees, and again I have a roadblock with this German ancesters

Roetman-Schiedam.
Hinrich/Henricus Ruthmann, + 1-2-1726 Ennigerloh (Duitsland)
x (1) 5-7-1689
Engel/Angela Merkentrup

uit 1e x:
Johann Ruthmann/Jan Roetman
* 27-5-1692 Ennigerloh
He went to Holland too

Roetman-Rotterdam.
Heinrich Roetemann, + voor 1-8-1860,
x
Theodora Borgholt

from this x
Heinrich Roetemann, * ca. 1835 Hannover,

Answers can also be given in German.

Thanks!

Petra Roetman.