How to add custom fields on a web form
Note: The following field types are not supported on web forms
- Multi-picklists
- Dependant Picklists
- Look-up Fields
1. Enable Custom Fields
1.3. Scroll down to Custom Fields and enable Custom Fields with the tick box.

Create a Header names for your new fields.
2. Create Custom Fields
2.3. Specify the type of field you would like and select 'Next'

2.4. Enter details for your field and select 'Next'

The fields showing a red bar are compulsory.
2.5. Set field security for your new field

2.6. Add to page layouts and 'Save'

3. Add Custom Fields to your web form
3.4. Select 'Save'
4. Make your fields publically visible
When creating a new field, the security settings just make the field visible to normal salesforce users. In order to make them visible on the public website form, you will need to follow the steps in: How to make a custom field visible on public web forms
5. Check your web form
5.2. View your new fields in the web form

6. Refresh Forms
If you are using the "Modern" forms, you will need to click the Refresh Form button on the Payment Form as per the following steps
6.2. Missing refresh button?
If the Refresh Form Button is not visible, go to Edit Layout on the Payment Form and add it from the Buttons option in the Page Layout
