If you're going to supplement with any vitamin it should be Vitamin D3. The RDA is way low for what is thought to be the actual required amount for optimal functioning (they recommend 600 IU when many competent sources say 2,000-6,000 IU is optimal). Vitamin D also has anabolic effects and improves mood. Most people are woefully deficient due to lack of sun exposure, diet, etc. Just make sure to get D3 and not D2 if you are going to buy as a supplement, and get the little gels if you can as opposed to hard pills as they absorb easier.
If you eat ample food including meat and fruits/vegetables you should be more than fine for getting vitamins other than D (you can check this by keeping an accurate Fitday log and checking out your typical daily nutrient intake), but if not then taking one or two good quality multi's should get you there.
I personally take 1 multi and 5-6 1,000 IU caps of Vitamin D3 each day in addition to my fish oil and have never felt better or been stronger.