Ankle lock is legal in Sambo and BJJ. How to do "krest" cross on one foot \ Sambo academy \Leg locks

I often use “Hail Mary” moves. If I get caught in back mount I always look how to finish my own leg lock. We call it “krest” (cross) and it’s often called “foot bar”. Ankle lock is legal in Sambo and BJJ. How to do "krest" cross on one foot Achilles leg lock https://www.youtube.com/watch?v=RN4_NQccefg Ivan Vasylchuk - Sambo Academy