A number of early Cadinot films had superb rape scenes. In his films, the raped boys struggle, suffer, cry, and scream. It's at once realistic and highly erotic. (There's no anorectal bleeding, as would perhaps be expected for realistic rough, forced penetration, but I think that omission is a reasonable artistic compromise.)
In "Le Voyage a Venise" ("Carnival in Venice"), an older bellhop rapes the exquisite boy protagonist. The struggle and subjugation are believable, the boy's pained facial expressions and cries made me extra hard, and the sex is beautifully filmed by Cadinot as always. It starts around 19:19:
Gay Classic A Carnival in Venice
The first scene in "Les Minets…Sauvages" ("Tough and Tender") is a dormitory gang rape. It starts with just one stud using the boy's mouth while everyone else watches and masturbates, but then it progresses to thoroughly satisfying rectal brutality perpetrated by multiple inmates. The boy sobs appealingly. The group dynamic is especially good, as they're not just taking turns inside the victim, but also encouraging each other, helping each other hold him down, and, like us, enjoying watching everyone callously and triumphantly hurt the victim with their penises. There are several other good rapes in this film also. Start around 9:15
Cadinot-Les Minets Sauvages
I think there are at least three rapes in "Les Jeu De Pistes" ("Hot on the Trail"), one of his scouting-themed films. I recall a scene with a hunter forcing two boys at gunpoint and a fisherman raping boys in revenge for the theft of a lure. Finally, I recall that a guy ties a pretty boy's hands up and violates him from behind while, comically, a cow watches. This scene is good if you particularly enjoy a short, slim, exceptionally boyish victim. Unfortunately, I couldn't find any video links for this film.