Dilexi decorem domus Domini, Father B. Jerabek:
When a person who is already baptized is received into the Catholic Church now, the ordinary profession of faith used is quite simple. The person states (without having to put his or her hand on a book of the gospels or otherwise in the position of taking an oath), “I believe and profess all that the holy Catholic Church believes, teaches, and proclaims to be revealed by God.” That’s how they juridically and formally enter the Catholic Church.
I recently came across the older form of the profession of faith for converts. Read it here.