All players from P4 up must now register with the SRU via their SCRUMS system. Registration for players in P1 to P3 is optional.
Details of how to do this as a parent can be found here: http://www.scottishrugby.org/sites/default/files/editor/images/scrums_registration_guide_youth_player_for_parents.pdf
Full details of the SCRUMS system are available here: http://www.scottishrugby.org/domestic-rugby/club-services/scrums-management-system
Getting past the login reCAPTCHA can be a little tedious but, clearly, a high level of security is required because of the confidential nature of the information being sought.
Please contact email@example.com if further information is required. With some 50,000 players to be registered, the response may take a day or two.