Kokutsu Dachi is a stance used by the Japan Karate Association and is a very common stance in the Shotokan world.
Kokutsu Dachi is also known as back stance.
The weight distribution of this stance is 70% on the back leg and 30% on the front leg.
It is important to keep your heels in line. If you pull back your front foot your two heels should touch.
Your back knee should be in a straight line with your big toe.
Your front knee should be just behind your front ankle.