what is the best technique for playing false harmonics and name some guitarist who use this technique well apart for tommy emmanuel
I think you mean to say artificial harmonics. Anyways, there are a lot of ways to do it.

Tapped harmonics are simply fretting a note with your left hand and then tapping the node with your right. Simple idea.

Steve Morse has a trick where he holds his pick between his thumb and middle finger, then uses his index finger to reach out and touch the node while still using a mostly conventional picking technique.

Jaco Pastorius would do harmonics on bass by touching the side of his thumb to the string, same part of your thumb you'd use for a pinch harmonic on guitar, but then pluck with either his index or middle finger. I know guys who do use a similar idea on guitar, but use their pinky to touch the node and hold their pick like they normally would.
Quote by nightwind
You must never double the leading tone ever. Failure to comply will result in a fugue related death.
Like slapping the harmonics? justin king just smacks the fret in the middle, and it makes the harmonic i do the same thing and it works fine. Just practice it slowly and your aim will be much better!