You will feel it in the tricep to some degree. However, the main emphasis is in the delts. To really feel this you must retract the shoulders before lifting the weights back behind you. This retraction helps to isolate the targetted muscles.
Try it on one arm only intitially and use the other hand to hook around over the top of the working shoulder to see if you can feel those delts working. Then if not, try the retraction again and work on your form until you can feel the delts working both through the shoulder muscles and with the hand of the other arm. Once you know you have isolated that muscle, isolate the delts of the other arm in the same way. Then, lift again with both arms.
Clare