This is pretty much a universal rule of poker. If a player wishes to show his hand to anyone at the table, the hand should be shown to everyone at the table. Players have a right to equal information, especially in tournament poker. 

Other players should not have to request this information.

The proper way to show your hand, if you wish to do so, is to simply place it face up on the table. 

Of course, this is in reference to showing your hand after the hand is over. You should not be showing your hand while the hand is still playing out. (In fact, if you are still in the hand, tournament poker rules state that you cannot show your hand to anyone, even if the hand has become heads up.)