I've got lots of experience with tantric massage, including yoni techniques. KK loves this kind of experience, and almost always experiences an intense squirting orgasm as a result. Be prepared for a long session, in which you are giving her pleasure.
Setting the mood, temperature, candles/lighting, etc. are important. We prefer coconut oil, specifically food-grade - it matches skin temperature easily, washes off, and does not irritate sensitive skin - it is also edible.
I've added and experimented with the technique of using a yoni egg, and a 'pocket rocket' vibrator for final clit stimulation, with excellent results. The yoni egg, especially larger eggs, allow you to relax a little and frees up one hand for nipple stimulation, etc. Without the egg, you'd need to maintain finger contact and pressure on her anterior vaginal wall during the experience. This can get tiring.
There are dozens of these videos on Xhamster - search for yoni massage. Here's a guide:
Are you new to yoni massage? In this yoni massage guide you will discover how to safely give or receive mind blowing female yoni massages.
karmatantric.com