Wondering if you could clarify, not sure if you mean French-language private schools, or schools that teach the French national curriculum leading to French Bacc.? If you want French language schools, there is also the possibility of bi-lingual if that would help.
Anyhow, the sticky at the top on schools gives the associations of private schools in switzerland and the association of private schools in Geneva, you can search both of these sites by type of language school, and read more to determine which national curriculem them follow. Repeating the two links here for your convenience.
http://www.agep.ch/eng/index.php Geneva private schools
http://www.swiss-schools.ch/ Swiss private schools
Also, will update the sticky with the new schools that have just opened in La Cote, between Geneva and Vaud, as there are more possibilities in this area now too.