In pill form, they’re usually fine during your fasting window. Chewier, gummies, or liquids may break your fast.
Rule of thumb is to take any supplements/non-prescribed pills during your eating window, as some of them work better with food in your system.
Vitamin D is fat soluable, so you need to take it with food that has some fat in it in order for it to be absorbed properly. You might as well just take all supplements during your eating window; the only exception I can see is if it has to be done at a certain time, like medications.