By starting consistently low, we manage to keep Chilli RKB responses consistently low. But when responder to RKB has two keycards and the trump queen, the response may still take us too high when controller has only one keycard, particularly in a minor.
Controller can avoid this by using the highest game zone side-suit bid to show values for slam and exactly one keycard. It also denies the trump queen – hence one and none. Partner then becomes controller.
One and none also implicitly denies the values for seven, since in that case there is no risk in using RKB.