I haven't found anyone in my family with the spelling of Rager. Franz Rieger came from Prussia in the early 1850's and settled in Ohio immediately. I've found many spelling variations on the surname, but all can be attributed to English speakers trying to write what they thought Franz said his name was: Reiker, etc.
I don't know who his parents were yet, but they didn't come over to the US with Franz.
Good luck with your genealogy. If you'd like to compare notes at all, check out my genealogy page at www.isomedia.com/homes/reiger/index.htm