I've got a couple of rangefinders I use on a regular basis. One is a DeJur that has no mount shoe, but a very nice fabric strap to go around the neck so that it can either hang down when not in use, or makes it easier to retrieve from a shirt pocket. It stays with my Vito B since it always has the Kontur finder mounted, so no room for a rangefinder.
The other is a Widor Universal that was made in Germany, and looks similar to the Voightlander model. It has a shoe mount, and I use it mostly for my MF cameras. The shoe has three mounting points so you can shift it left or right to suit whatever camera you are using.
Kodak made one that was verticaly mounted, to clear any topside obstructions on the camera. The ones made by Ideal are what you see mostly for sale, but again, no shoe mount. Norwood made one that while designed to be used as a calculator for flash bulbs, it can double as a rangefinder in a pinch, and is vertical like the Kodak. Kodak also made a more conventional model that is found more often.
PF