Since you're referring to my FED2 "essay", I guess I could provide an answer.
The text of the essay was intended as a humorous report, not a detailed technical advice.
Anyway, the RF on my example *WAS* off - when the images concided when I aimed at my friend about 1,5 meters away, the engraved scale said something quite different - obviousl the RF was off.
Then I aimed at a far object, and focused on it (in the RF window) - the distance scale was again off - or it wouldn't align the RF patch at all, I don't really remember.
In short, I fixed it, taking several test shots, using a ground glass & a loupe, etc..

If you're satisfied with yours, there's no reason to mess with it.

Regards,

Denis