Multisite: How to define and limit a Custom Post Type to specific sites?

I have 2 sites on a Multisite network:

A) Primary.com
B) Secondary.com

The primary site has a custom post type called, “primary_site_employees.” I do not want the Secondary site to have access to the “primary_site_employees” custom post type. (The Secondary employees do not work at the Primary.)

I’m prepared to create a new custom post type called, “secondary_site_employees.”

How can I have custom post types show up only on a specific site?

Thanks in advance!