1. Go to Settings > Kitchen Settings > Kitchen Locations.
2. Click Add new (only visible while you have unused active slots; the button shows how many are left).
3. Under Location details enter the Name, and set Is Active? and Allow customers to select this kitchen.
4. In each fulfilment section (Meal Prep, Retail / Wholesale, Catering, Realtime, In Store Menu — only the sections for modules you have) switch on the weekdays this kitchen fulfils. All weekdays are on by default for a new kitchen.
5. If Root Planner is connected, pick a Root Planner Hub or leave --No Hub--.
6. Click Save. You are taken to the kitchen's edit page with a green Done!.

You need the Edit Kitchen Locations permission. Saving fails with "Have more active Kitchen Locations than N allowed" if the new kitchen is active and you are already at your limit.