Unlike the 5 and 7 hole cording feet, #25 & #26 in your Madam Sew kit, this foot hold an easy to manage three cords.
Looking at the foot you will see that there is a small bar atop three grooves in the front of the foot.
This is where you cords are placed.
You can loosen the screw on the left of the foot to allow for a looser grip of the top bar across the cords.
The is particularly useful when working with larger cords. For smaller cords, such as embroidery thread ad tighter grip is preferable.