yup angle the foot in and load the hip , This is really a variation kick , not a standard by any means , one of my oddball kicks .
Its a weird combination of roundhouse , straight kick , and back kick dynamics all in one .
Imagine a straight front kick snapped out straight , then imagine what would happen if you rotated the hips , kind of like a side kick that pivoted in rather than thrusting out , then taken a step further and the knee starts going down towards the floor like a Back kick , so the pivot is arching over and down into the stomach ......
If I get a chance i`ll tape it , sounds like nonsnese i know but it can be thrown in relatively short range with devestating penetration .
As for foot position If not kicking with the shin (most often) the proper Shotokan way is ball of the foot , I do this for this kick and for traditional work , I like it but many have trouble with the flexibility at first .
I personally dont like the instep method taught by many MA
Heh is hard to communicate with words ... generally all my front kicks come from the same position the knee being straight up in front kick position foot up and toes back
, the hips and variation come from there .
back kicks I can do the same but also have the variation Of Muai Thai style roundkick with more swing and momentum . depends on wether deception or power are called for , sparring tools ....