From the Setup tab, choose Custom Fields and click the Create Custom Field button.
Once you are in the custom field editor, enter a field name and select a type.
Field Name: This text will be displayed on the Public Signup Page to prompt the user for input.
Field Type: Text, Dropdown or Radio Button
There are several options to control where your custom field will appear. All display options are set to no by default.
Display Field Data on CSV Export: Yes or No. If Yes, the field will be included in the Subscriptions CSV Export.
Display Field Data on Statements: Yes or No. If Yes, the field will be displayed on your customers’ Statements
Display Field Data on Invoices: Yes or No. If Yes, the field will be displayed on your customers’ Invoices. (Invoice billing is available starting on the Plus plan.)
Display Field Data on Customer Portal: Yes or No. If Yes, the field will be displayed on your customers’ Billing Portal
For Radio Button and Dropdown type fields, you can configure the values that the customer is allowed to select an option from in your product.
Once you have created a Custom Field, you will see the option to display it when editing your Public Signup Pages. Once you have done so, you will see the field at the bottom of the signup page: