The route has 4 checkpoints:
Start/ Finish with hands on the Knoydart Foundation plaque outside the foundation shop in Inverie.
Other 3 checkpoints (completed in any order): 
Ladhar Bheinn summit Cairn (Not trig point) 
Luinne Bheinn summit 
Meall Buidhe summit Cairn
(It should be noted that all 3 Munros have subsidiary summits that can be mistaken for the checkpoints in poor visibility.)

https://heightsofmadness.com/2012/08/20/the-knoydart-3/