A new penalty area has been marked on the course with red stakes around the willows on the 7th hole. If your ball lies in this area you may drop outside the penalty area under penalty of one stroke.
In general, a drop is taken within two club lengths of the point where the ball last crossed the line of the penalty area (the reference point). Remember that the burn on the 7th is also an unmarked lateral penalty area, the edge of which is the bank of the burn. The other option is to drop (under penalty) the ball as far back as you like, keeping the reference point and the pin in line.
You do not have to find the ball to take relief under penalty, but you should be certain that your ball came to rest inside the red stakes.