Long press on a contact's number to cloak / uncloak a single number.
The icon positioned to the right of a contact or number shows the associated cloaking status:
By design NO information is transferred off your smartphone by Cloakfone. Automated synchronization requires the transfer of data to cloud based servers, hence the aforementioned two-step export / import requirement.
Subject to demand an automated synchronisation version may be provided. If it is however it will be a separately identifiable version.