4 factors need to be in check in order to be able to have the best range of motion while the hip and entire surface of the feet are on the machine:
1_ how high or low do you put your feet?
2_ how close or distanced your feet are from each other?
3_ how much internal or external rotation of the hip do you have?
4_ how much dorsiflexion or plantar flexion do you have?
keep in mind that changing each of these variables can affect the others