I'll just paste my question from the comments.
when I attempt to put my leg under the controlling opponent he automatically responds by turning his body with mine, keeping my leg from getting under.
I'm not sure how much leverage is lost from not having my leg under, or if it's a crucial point for the technique (I saw ari bolden demonstrate it without knee under hip).
Any tips on the technique, and getting the leg under the hip? and is it necessary?