I mix it on the bank. Usually enough for 1/2 day because it tends to go sour after a while in the heat.Just add water, then 10 mins later you may need to add a drop more and you're ready to go.
A brilliant trick on well stocked waters is to add mixers to the Vitalin mix. In calm and light wind conditions the mixers will float to the top, periodically as the ball breaks down, carrying with them bits of Vitalin,leaving a trail of goodies from top to bottom. You will usually see fish swirl at the mixers before following the bait trail to the bottom and eating your hookbait. It really can be this good in the right conditions, so give it a go, especially on "hungry" waters where the fish compete for food.They go absolutely mad for it.
Best of luck,
Jake.