How to add custom field on Role doctype it's not working using Customize Form

1

I am trying to add Country link field to Role doctype. I used customize form for that, but this field not added.
When I checked custom fields it showing me entry for the country but not reflecting the result on Role doctype

role
role1151×555 28.2 KB

Role1
Role11160×294 22.5 KB

2

Why you are customising Role DocType?

What is the use case?