where to hit someone to get the perfect knockout punch , tried and testedplease

The point of the chin works for me.

Lewis/Radman 2 and Lewis/Tyson those ko really hurt my chin to see it

One counter hook.. Donaire v.s Darchinyan

right on the side of the chin. they call this ''the button''. if you hit someone here, their head snaps quickly to the side and they go out.

looping overhand to the chin

For most boxers, a slight angle on the point of the chin. For some, a shot to the side of the temple.

Blogbaba has it with point of the chin. A good example of hitting someone perfectly would be Marciano is Suzy Q right hand vs Walcott or Thomas Hearns perfect right hand vs Duran.