From my reading of the rules of golf, you should add a two stroke penalty to your score and then post it to GHIN, or whatever handicap system you use.
[from usag.org]
27-1. Stroke and Distance; Ball Out of Bounds;
a. Proceeding Under Stroke and Distance
At any time, a player may, under penalty of one stroke, play a ball as nearly as possible at the spot from which the original ball was last played (see Rule 20-5), i.e., proceed under penalty of stroke and distance.
Except as otherwise provided in the Rules, if a player makes a stroke at a ball from the spot at which the original ball was last played, he is deemed to have proceeded under penalty of stroke and distance.
b. Ball Out of Bounds
If a ball is out of bounds, the player must play a ball, under penalty of one stroke, as nearly as possible at the spot from which the original ball was last played (see Rule 20-5).
c. Ball Not Found Within Five Minutes
PENALTY FOR BREACH OF RULE 27-1:
Match play - Loss of hole; Stroke play - Two strokes.