Lying prone or sitting
Ask the patient to wear shorts.
Posterior to the patient in lying prone and possibly anterior to the patient in sitting.
Please lie on your stomach (or sit). In order to (explain the reason, e.g. assess the blood flow near your knee), it would be helpful for me to take your pulse behind your knee. May I place my fingers on the back of your knee? (or point to the demonstrated area)
Guide the patient to either lie prone with the knee flexed and supported or sit with the knees flexed. Gently press your finger tips deeply, but without causing pain, into the posterior knee. Palpate the pulse if possible. Compare the pulse to that of the other side.
VH - Popliteal artery