Custom fields is permission based in Rindle. By default, the account owner (the person who created the Rindle account), will have access to custom fields. The account owner and any admin can grant users Custom Field Manager permission when managing their user account.

Go to your Account

Then select Users from the navigation menu

Click on the user you want to make a Custom Field Manager, and select Custom Field Manager from the permissions list

Click Update to save the change.

Note: this permission can also be set when creating a new user account.