To create a roster in a private channel you first need to add the rosters bot to the private channel so that it is able to post messages. To do this follow these steps:
- Go the channels settings, click on the integrations tab and then on the “Add an App” button
- Find the Rosters app in the list and click on “Add”
- Click on the Rosters app from the sidebar, then click on the channel selector and select the channel the private channel
- Click on the “Add roster” button
- Create your roster
