If you have a high IQ, and have a certified IQ score, would you put it on your resume? Or would you see that as being pretentious?

I would recommend that you put your certified IQ score on your resume, along with your other credentials. The resume is not the place to be humble; it’s the document that is designed to showcase your capabilities. Furthermore, employers are looking to hire intelligent people, so a first-rate employer would likely be impressed, rather than offended, by your high IQ.