פירוש על במדבר 6:27

ושמו את שמי AND THEY SHALL PUT MY NAME [UPON THE CHILDREN OF ISRAEL] — i.e. they shall bless them by the Proper Name of God (i. e. when uttering the blessings they shall use the Tetragrammaton and no substitute for it) (Sifrei Bamidbar 43).

I will concur. But one should not explain that He would bless them Himself, because what would be the purpose of the blessing of the kohanim if Hashem were to bless them.