I guess that it moves a vertex to intersect of plane, not edge 
UPD: It can be done in a more simple way.
Pick vertex to move (on target object)
Intersect [LMB]
Pick edge to set direction (on target object)
Pick plane to intersect (on reference object)

UPD: It can be done in a more simple way.
Pick vertex to move (on target object)
Intersect [LMB]
Pick edge to set direction (on target object)
Pick plane to intersect (on reference object)