Who made this doll and when?

My mother in law found this sweet little doll in an antique store. She is bisque and all fingers are intact with no chips. She is 5-3/4" tall. She has an RB on the back of her head and on her back. She has a closed mouth smile and a jointed neck. I think she has been restrung and had no original clothes. She just had a piece of lace wrapped around her for a dress. Her eyes are glass inserts but do not shut. Her eyebrows and lashes are painted on as are her socks and shoes. Her hair is mohair and glued on. I have tried to research her but haven't found one exactly like her. One source said the RB marking was for Rempel and Breitung a German company, however I couldn't find out anything further on that lead. We just think it would be interesting to find out where and when this doll was made.