The check and training pilot was demonstrating a single engine approach to a simulated helideck in crosswind conditions and towards the setting sun. As the aircraft entered the flare for landing the pilot misjudged the approach and adopted a higher than normal nose attitude. During the manipulation of the controls to complete the landing the pilot lowered the collective control whilst holding aft cyclic control. This resulted in one main rotor blade striking the base of the vertical fin. The pilot felt the contact but assumed it was a tail skid strike. The skid was inspected, and when no damage was found, the flight was continued. The blade strike was discovered after the flight was completed. The possibility of a blade strike on the tail during single engine landings is a known problem and is covered in Sikorsky Aircraft Customer Service Notice 76-62. The pilot was aware of the contents of this notice.