You should ask the french consulate if you need multiple entry visa. It’s basically the same price but they indicate that you get to leave France and come back. You’ll probably need to have proof of transportation out of France (ie, plane, train ticket). I went to Amsterdam, Belgium and Luxembourg on a single entry visa from France but we drove there. I don’t know if they check passports on trains in the EU countries. However Geneva is in Switzerland. You can go transit to another Schengen country on a train but you can’t get into the country without a Swiss visa unless they don’t require one for your country.

Hope this helps.