Contact the ball below your knees and above your upper ankle within your hitting zone (see forehand stroke mechanics if you don't know what that means). The ball should leave your racquet and hit the front wall anywhere from 7 inches to 12 inches depending on your power, the vertical angle at which you hit it, and other factors. The ball then travels away from the front wall, bounces once in front of the foot fault line (approximately) and then takes its second bounce around the dotted line.
The pass-kill shot is a great trade-off between the pass and kill. If you're having trouble skipping too many kill shots, and your opponents seem to be tracking down your passing shots too easily, then maybe it's time to try the pass-kill. Contact the ball lower than you would a pass, but not as low as you would a kill.
Here's a video example of the deadly pass-kill shot: