The back hand slap:

The back hand slap is best employed to a potential threat stood slightly to your to flank. The back slap works best from either; the hand on the chin position or from the hands together, in front of the chest position. The target area for this strike is the facial area.
To slap just strike straight out to the target, from where ever the striking hand is, giving off no telegraphic intention. Just move in the direction of the strike and whip your hips in a split second before the strike lands. This will ensure that your full body weight accompanies the same for maximum effect.

The back slap can also be followed immediately by the forehand slap in combination for maximum effect. Performed in this way the back slap is thrown first as previously described; but is now immediately followed by the fore hand slap as one beat. In other words if you think of the back hand as one beat and the forehand as a second beat then it would look like this; one…two…instead of that the combination is thrown as one, two using an almost simultaneous action. In this way the second strike gathers impact power from the momentum created by the first shot, for twice the effect. Again we are looking at the facial area as a target, this will create shock impact to the CNS but with leave the recipient relatively unharmed other than perhaps a temporary altered state of consciousness and slightly red faced.