For what it's worth, while stationed in Germany for five years my genealogical research has led me to identify at least five different Reidenbach family lines that emmigrated to the United States as well as a city in Switzerland that goes by the name of Reidenbach. I have also been able to ascertain (with some degree of accuracy although not 100%) the meaning of the surname Reidenbach.
The five family lines oddly enough come from five different parts of Germany. The Reidenbach family line that is associated with Lancaster area of Pennsylvania came from a town in southwestern Germany named Zweibrucken. The other five families came from Munich (or Munchen), Bremen, Meddersheim/Barweiler (located west of the city of Frankfurt) and the city of Frankfurt am Main (where my family line is said to have came from) and for some curious reason they all settled in the west-central Ohio/east-central Indiana area.
According to my research, the surname Reidenbach is of German-Jewish origin. The "bach" part of the name means "small river or stream" while the "reid" part has had two different meanings attached to it - either the color red OR fast, swift. It is my belief that like most immigrants to the US who took their surnames from the towns they came from or professions they had in the "old country", the Reidenbach family either came mainly from the area that is named Reidenbach, Switzerland and emmigrated to the different parts of Germany or they came from an area that is said to have had fast moving streams or rivers close by. While neither theory can be proved (at least at this time), it does give a general direction for one to start their research in Germany.
My family line of Reidenbach came from the Frankfurt am Main area. Phillip Henry Reidenbach and his wife Mary Lawall came to the US in the mid to late 1800's. They had several children one being gg-grandfather Philip Reidenbach. He married a woman from the Delphos, Ohio area by the name of Fisher where they also had several children one being my g-grandfather Benjamin Reidenbach. I'm unsure at the moment who Benjamin married however he and his wife had at least two children .. Robert and Richard Reidenbach. Richard (Dick) Reidenbach, my grandfather, married Catherine Murphy and they had three sons ... Dick, Benjamin and Robert. Robert being my father. This is my lineage to the best of my knowledge and posted here without notes. If anyone has any additional information that ties into this Reidenbach family please feel free to contact me.