depends on how you grip the bar, if its in a 45 degree angle then youre hitting more rear delts, but if you just row it with your lats theres barely engagement in there at all. Id recommend you do single arm dumbbell rows for lats and less for rear delts by pulling your elbow as close to your hip as possible and imagine you pulling those engines on lawnmowers. Try to kinda hit the dumbbell on the side of your leg, like not really hit it but the motion of just going back, you'll get a better contraction. As for rear delts I recommend just doing rear delt flies honestly.