Jackie isn't the only RTA cast member or guest star who have gone due South. Others include (along with episode title):
Roger Dunn (Bert Potts in several episodes) - Store Owner in "A Cop, A Mountie, and a Baby"
David Fox (Clive Pettibone) - Rev. Albert Barrow in "Bird in the Hand"
Frances Hyland (Louisa J. Banks - Sara's Nanny Louisa) - Fraser's Grandmother in "Letting Go"
Graham MacPherson (Dr. Snow in the sixth and seventh seasons) - Dr. Martins in "Hawk and a Handsaw"
Shawn Mathieson (Jimmy in "Return to Me") - Sid in "The Promise"
Gordon Pinsent (John Hodgson in "Someone to Believe in") - Robert Fraser in numerous episodes, became a regurlar during season 3/4
Wayne Robson - Damon Cahill in "Asylum"
Cedric Smith (Alec King) - High-ranking Mountie in "Perfect Strangers"
Ron White (Mr. Tyler in several first season episodes) - Kevin Spender in "I Coulda Been a Defendant"