I must say kote hineri (sankyo) is great for controlling uke if your doing the technique properly. You can make uke move in any direction you want which is great if you want to keep him on his feet as you can move him places or you can use him as a shield against other attacks.
Arunabha Sengupta you should not need to close your fingers. If you have ukes right hand then the thumb of your left hand should be at his wrist on the thumb side and your fingers should be grabbing the muscle on the little finger side of his hand, also if his hand is still a little big then use your other hand on ukes fingers (it should look like your holding a sword) and twist them.
Now which taoshi (take down) method are you using, because all you need to do now is "suppress his elbow joint with your right hand from above and turn your body to your left by drawing back your leg." (Kisshomaru Ueshiba, Aikido).