Couple of general points re: vitamin hechsher.
1) flavored vitamins need hechsher.
2) non flavored... Machlokes, as usual. Reasons to permit: not derech achila, done for medicinal purposes, any tarfus is now pogum.
3) reasons to forbid: achshevei, not a real medicine, tarfus is possibly not pogum, it's just the rest of the pill that's pogum.
Bottom line, I imagine the OP is posting this because he needs an answer tonight. One way around these issues, is to wrap the vitamin in a small piece of tissue and then swallow it that way. That should be ok even according to more stringent opinions. I can't vouch for everyone, but I believe even r fishel Hershkowitz, who is machmir, permits when wrapped.
Sorry for any brevity, but I'm posting from a mobile device.