Rosaire was probably used at least occasionally in the early 20th century, though it's very rare in France today. You're probably much more likely to meet a 90-year-old woman than a younger woman named Rosaire. Plus with what Rene said, it seems to have been used for males as well.
Maybe the situation for Rosaire is different in France's former colonies, such as Haiti and a number of countries in Africa. People there tend to use older French names more often than people in France do.
This message was edited by the author on June 26, 2011 at 9:59:13 AM