I found a site saying it is from Rother, a Germanic firstname, composed of
hrod and
her , meaning "famous army".
sources:
http://www.meertens.knaw.nl/voornamen/VNB/index.php?id=16199&act=zoekenhttp://www.meertens.knaw.nl/voornamen/VNB/index.phpfreepages.genealogy.rootsweb.com/ ~bgwiehle/siebenburgen/sbs-namen/sbs-namen-cat12.htm