I don't think it's possible to be that precise using the markings on the lens, you might be spot on in your close focus. Best way to tell is to take some pictures and see if the camera is close focusing or far focusing. If it's off, and probably not by much, then try to adjust it again to make it spot on for close focus. You can put a ground glass on the film rails or some wax paper to act as a GG, keep the back open and focus on something about 1 meter away with the RF, then check the GG to see if it's in focus. Adjust until you get this spot on. After you get it right, double check your infinity focus. There's a screw that adjusts the difference between infinity focus and close up focus but it is not easy to get to. You have to take the top plate off the camera to get to it. It usually does not need to be adjusted and if it does it's best to leave it to the experts. Good luck, Bob.