If you have used Document Customizer prior to installing the Shipping Manager, or activating the feature of customs tariff, then the standard setup for custom tariff won’t be a part of your setup in Document Customizer.
But you can manually add this.
We do this under actions, add setup for new document types, and press on custom tariff setup.
Please note that this action will only be available if the shipping manager has been installed and the custom tariff feature has been enabled.
Now, standard setup with the new templates for custom tariffs has been added to your Document Customizer setup.