Ray Ban RX 8613
comes in two lens sizes: 51 mm and 53 mm. If you tried on the 51mm and it is too tight, the 53 mm should work fine. Ray-Ban RX 5095
also comes in two sizes: 50 mm and 52 mm. Same thing: one is smaller and one is larger. If you would like to compare these two models: RX 8613
in 53 mm size is larger than RX 5095
in 52 mm size.
In my opinion both these frames even in the larger size feature medium fit. If you are looking for a large fit, I would recommend Ray Ban RX 5114
in 54 mm size.Ray Ban frames
made from plastic usually can be slightly adjusted. But not when they fit too tight. If that's the case, just go with a larger eyeglasses frame