The marker is applied to the (place idfk, like right under the base of the neck like kind of between the shoulders but above there, just /pic) of both the King and the Queen at their coronation.
Heirs/Trainees don't get the mark on their back until they're officially Coronated as King/Queen, however the Trainees do get it on their left palms on their official K/Q in Training Coronation
When a King/Queen retires, their marks stays with them.
If a King/Queen is disgraced (as with Victor), their marks are forcibly removed by carving off all marked skin (back+palm)