to all you native English speakers: Would 'he sat on the rim of the chair' be a possible translation, too? (esp. while thinking of one those wooden, round bistro chairs with a slightly elevated border as in the pic below - or a bar stool...) Or does that sound strange? (photo from www.trentfurniture.co.uk)
Rim is strange to my ear, it's used more for containers like the rim of a cup, or the rim of a toilet seat. Edge is used for flat surfaces like a chair. I would also say "edge of the chair" sounds strange too, "edge of the seat" seems much more natural. Chair sounds more formal, like armchair/lounge chair where you relax into it, whereas seat sounds more informal, like a fold down seat at a sporting event, where one is more likely to be on the edge from excitement.