Choosing the right film for Rangefinders
Your choice of film really does depend on the situation at hand and what look you're trying to go for. So I really don't believe there is a right or wrong film for a rangefinder. I personally use anything between ISO-50 and ISO-400, even up to 800-3200 if the situation demands it.
As Alex said, it really depends on your camera and your shooting situation. What is the choice of speeds on your rangefinder? My FED-2 only goes up to 1/500 sec. So, on bright summer days, shooting any slower would mean that my f/stop needs to be small (f/11 - f/16) and my ISO needs to be less sensitive, like ISO 50 or ISO 100. If the light is more dim, I could get away with using ISO 400. If the light is just too bright, the film rather fast, and you want a more open aperture for more shallow depth of field, using a neutral density filter or a colored contrast filter helps to block the extra light.