My summery of this subject in that chapter
He brings it twice once regarding when doing kedushin on money and once when doing kedushin with a ring, he says: to hold her right hand in his left hand and hold the money/ring in his right hand
By money: he should say hari at mekudeshes li... then but the money in her right hand and let go and then say kdas moshe visrael.
By ring: he should but the ring on her finger and say the whole saying, and then let go when he lets go she acquires it
I guess the reason might be that even when the groom is holding the ring since it is one her finger (she can take her finger away with the ring) it already belongs to her before he finished saying mekudeshes li bze, but if he hold her hand she does not aquier it yet
On many weddings i do not see it done
Why is it not done?
Was it always like this? (If not when and why did it start?)
Are there groups of Jews that do it? If yes which?