To create a registration dot simply create an 8mm circle with a black fill and no stroke. If you have a black or grey background you will want to use a color that contrasts your background best. Registration dots are dots the cutter uses to recognize exactly where the piece is on the cutter and also to recognize if there were slight distortions in the printing process. The most basic dots you can use are 3 dots around the piece as seen in the example screenshot. This can be used for most all cuts on the machine. The more distinct you get with your cutting the more registration dots you should have on your piece. Do you have a specific curve that you think may cause problems if distorted? Place a registration dot by it. You can have as many registration dots as you want on the piece, but they must be a minimum of 3 inches apart from each other for the camera to read them properly.
For more information on registration dots please check out this Zund video