RF templates are assigned to which Mist configuration object?

 According to the Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide1, RF templates are assigned to sites, which are logical groupings of devices based on physical location or other criteria. RF templates allow you to configure RF parameters such as channel width, transmit power, and data rates for multiple devices at once.

References: https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/17-2/config-guide/b_wl_17_2_cg/rf_templates.html