The RSTC form can be found
here, and is attached.
Age 65 is not the cutoff...but rather 45! Question 2 asks if you are over 45. If so, go to Box B. Box B asks if (a) you smoke, (b) you have high cholesterol, (c) high blood pressure, or (d) you have a close blood relative with heart problems. If you answer Yes to any of those 4 questions, you need a doctor's signature on the form.
Also, question 10 asks if you take any prescription drugs (other than birth control or for malaria); if you answer Yes, you need a doctor's signature, regardless of your age.
It is rather hard to "pass" this questionnaire....so get a doctor's signature and keep it with you on all dive trips. It is good for one year from the date of the signature.