There's no feature for tipping on italki, therefore the best way to do it is by scheduling a lesson

with her, and sending her a message to let her know that you had to schedule a lesson just to 

tip her and not to take that lesson for real :)

If the price of her lesson is not what you have in mind for the tip, ask her if she could offer a 

lesson for a price that matches the tip you intend to give, and book that lesson as I explained

above, and confirm it after its time passed as any usual lesson.

Wanda suggested that I tell my instructors name in-case others want to use her too, she would love that .

Her name is "Carmen B. Azuaje J" from Venezuela, she is really the best.   She is very patient with me, and keeps pushing me each session.    I hope you all sign up.