Sasless, having gone through this in the real world just the other night, I had my 'plan' worked out as best I could by what fuel was indicated, using a 200kg/hr burn rate and the eta to the airport.
My FRF was 105 kgs. I 'planned' to land above that figure, and I did.
As long as the fuel remaining was more than the fuel needed, I was happy. If the possibility arose that the fuel needed to land there was going to be below my FRF I would be looking at an alternative landing site. As it happened it would have been at the closed airfield that we had to fly over to get to said airport. If that airfield wasn't there and I only needed an extra 5 mins (15kgs) to get the the airport, I would have used the reserve. Yes I would have landed below my FRF, but it wasn't planned! (Report would have been filed)
As far as ATC was concerned, they were warned off by the previous ATCU that I would be coming in for fuel in order to rtb and the conversation at one point went;
"We are talking with a handling agent and may have problems getting you fuel"
"That's ok, I'll be coming in anyway as I haven't enough fuel to go anywhere else"
No other type of call was necessary as there was no distress or emergency, however, if I had to go into the FRF I would have given the call, in order to get any priority needed.
Now, according to your land right now interpretation, I should have be thinking about landing in a field immediately!
Seems weird to have a reserve fuel that according to some, should never be used!