Here’s lady Eva’s guide to evocation. She works without the circle and triangle. I’ve used this for 12 evocations. It works great
If you perform a LBRP the circle created from that ritual is Enough to be effective.
You can also turn clockwise in a circle and say may no spirit penetrate this circle that I do not give consent.
That usually works. I don’t mean to alarm you. Go with what you’re comfortable with obviously.