No, IMDb will not help. Nowaday, it only contains a single doubtful entry for Rita Waterhouse in "Gone With the Wind" (Rita Waterhouse - IMDb). Until 2006, there was a filmography under that name, about 10 film big, as director ("Because She disobeyed", "I Know What I Want", "It Began in Brighton", "Amidst Us", "The Pink Fox" and maybe some others), but the name and films were removed after that. And unless mistaken, you cannot trace this name and these films elsewhere on the Internet, with reliable sources.
My belief is that this Rita Waterhouse is a hoax!