customize the phone field type in wp job manager

I need to get a freelancer to do the following : Customize a phone field on [login to view URL] Our users should be able to select their country from the dropdown box, as showed in the picture, and then the field should show the user in what format the phone number should be. for now it should only display phone numbes for europe like this : [login to view URL] It should be a very easy job for the right freelancer . I need a full guide to how you got it to work before releasing payment, so we can implement in on our other sites. The documentation for how to make it work: [login to view URL]