How can I add a Polygon Cutout area in footprint?

I am making a footprint of a SMT component which as build-in antenna,
The datasheet says the antenna area on the PCB should not be covered by copper.
Manufacturer supplied Altium footprint library contains an area on Top Layer with kind of ‘Polygon Cutout’.

How can I achieve this in upverter ?

Got the answer, keep out layer

Hi @trulyliu,

yes, they keepout layers are what you are looking for!