When we stroke on the right side you place pressure through the right heel and pull from the right hip and rotate the torso to the right side. When we stroke on the left we place pressures through our left heel, pull from the left hip and rotate the torso to the left.
It is important to keep all 10 toes pressed forward to keep the pedals straight which ensures the rudder is straight.
Remember the rudder is about 15cm long, if it's out a couple of degrees it will cause unnecessary drag.