Tearing by oneself or by another

In the "Birkei Yosef," it is written that it is preferable for another person, whom the mourner is embarrassed before, to perform the tearing, thereby making the mourner feel his mourning more intensely. However, in the "Aruch HaShulchan," it is written that it is preferable for the mourner to tear by himself (perhaps because the commandment is more fulfilled by oneself than by a messenger, or because this way he suffers more, or because he holds that the reason for tearing is to have something to ease his sorrow, and by himself, he eases it more).

Therefore, the custom is that a person from the Chevra Kadisha begins the tearing with a knife, and the mourner himself continues the tearing, for his father and mother until the heart, and for other relatives, he tears a handbreadth by hand. (A handbreadth is required because tearing less than a handbreadth is not considered tearing.)