My blood work around xmas had my Vit D at ~12. I got this:
Solgar Liquid Vitamin D3 - 5000 IU per serving.
My latest labs had my Vit D at 42. I would say I remember to take it 3-4 times a week...
it is seed oil based - sunflower seed oil. But, you are taking 1 mL - so 1/15 of a tbsp. I think someone once mentioned an olive oil based Vit D... maybe they'll chime in here.