Cook the entire batch of vine, do the same with the leaf, then drink some vine, wait ~10 minutes and drink some leaf.
For one serving, 50g vine should be good. With the leaf, 50g may be too much or too little, depending on the leaf. If you don't know anything about your leaf other than that it's Chacruna, you'll have to find its potency by trial and error.
Generally Hawaiian leaf is more potent than Peruvian.
P.S. I think this post belongs more in the Welcome Area than the Research section.