When taking a drop the player needs to state his intentions to his fellow competitor.

Please note the last line of this rule!

27.2. Provisional Ball
* a. Procedure
If a ball may be lost outside a water hazard or may be out of bounds, to save time the player may play another ball provisionally in accordance with Rule 27-1.

The player must inform his opponent in match play or his marker or a fellow-competitor in stroke play that he intends to play a provisional ball, and he must play it before he or his partner goes forward to search for the original ball.

If he fails to do so and plays another ball, that ball is not a provisional ball and becomes the ball in play under penalty of stroke and distance (Rule 27-1) ; the original ball is lost.