The front kick is not employed too often in JKD sparring because the on-guard stance does not allow too many opportunities for its use. But it is a effective weapon against many fighters who don't protect their groin area well.
Although the ball or toe of your foot can can be the point of contact, predominantly the instep and sin are used. It can be delivered more accurately than with the toe or ball. Your foot will be travelin upward betwwn your opponent's legs making it almost impossible to miss the target. (Lee & Uyehara vol 1 1991)
