The propolis mat sits under the lid. The raised parts of the propolis mat make bee space between the frames and the mat. The mat itself has small gaps which the bees will fill with propolis. Once the mat is full of propolis, you can freeze it and crack the propolis off. Autumn is the peak time for propolis production.
You may find that you have better results if you stick a match stick between the mat and the lid. Please let us know in the customer comment section whether you want an 8-frame propolis mat or a 10-frame propolis mat.