This leg-lock is applied as you escape your opponents guard.
Stand up and place your right hand on your opponents left knee. Push down here to cause them to uncross their feet.
Once your opponent has uncrossed their feet, take your right arm round their left ankle so the top of their foot is under your arm-pit. Your right hand should be resting on your chest.
Sit down so your opponents left leg is between your legs.
Take your right leg round your opponents left leg. This foot is used to prevent your opponent from sitting up.
Place your left hand just below your opponents knee. Now grab your left wrist with your right hand as shown. To apply the lock simply lean backwards.
A variation to the grip used is to hold your own gi as high as possible with your right hand.