Other than the president of the U.S., many politicians (including Jefferson Davis, sworn in as president of the Confederate States of America in 1861) used the phrase "So help me God" when taking their oaths [REF].
Given that nearly every President-elect since President Franklin D. Roosevelt has recited the codicil, it is likely that the majority of presidents-elect have uttered the phrase[REF] (as well as some vice presidents, while taking their oaths).