I just write in the remarks of the log book.
SEP 1 hour with instructor sign and lic number.
Some people put SATIS in but I got told by an old hand examiner not to put any comments about the quality of flight as it then means you are signing them off as competent. Your job is just to sit next to them for an hour to comply with the regulations not to test them on thier flying skills.
Its an old well run debate on PPrune what you are actually meant to do on these flights. If the person is competent they can very enjoyable, if the person for a better word is ****e you get into a grey area of rule interpretation which there are various opinions on. It is actually very rare you do get into "discussions" with the pilot if they are requiring additional training. The couple that I have had that did require a wee bit more, finished the discussion before it started by booking additional lessons before coming through for the debrief. But if they hadn't and refused my suggestion of futher training I would have signed thier log book as they had complied with the requirements of 1 hour dual.