Open any incident to verify that the field was added to the incident ticket view. All the fields are displayed vertically in the selected section. If you add a large number of custom fields, only 5 fields are displayed on the view, and the rest are hidden. You can click the Show More link to view all the fields.
You can edit the custom field inline like all fields on the default view, by clicking the edit icon. However, fields in the Assignment area are displayed on an Action Blade for edit.