Set the bar on the smith machine at mid-thigh height and stand in front of it with your feet spaced shoulder-width apart and with a slight bend in your knees.
Grab onto the bar with an overhand grip spaced shoulder-width apart and rotate it off the pins.
With your shoulders positioned down and back, shrug the weight up as high as you can until you feel a strong contraction in your traps. Lower the bar back down and repeat.