Generally speaking, R' Yosef Karo doesn't quote authorities by name in his Shulchan Aruch, but rather focuses on what the halacha is in the Shulchan Aruch and leaves the various opinions and rationales to be explained in his Beis Yosef.
In going through Hilchos Pesach, I stumbled upon the first exception I've seen to this, in OC 460:2 (translation is Sefaria's):
הרא"ש היה משתדל במצת מצוה ועומד על עשיית' ומזרז העוסקים ומסייע בהן בעריכתן
The R"ASH would personally deliberate on the Matzot Mitzvah and oversee the production, inspire those working and assisting them in the flattening [of the dough].
Is this unique in the Shulchan Aruch, or are there other places where he refers to an authority by name?