Riddle, who grew up in the NSW north coast town of Lennox Head, started his career with Canterbury.[2] He was a member of the Bulldogs' 2001 Jersey Flegg premiership winning team and scored the winning try in the grand final win over Cronulla.[3] At the World Sevens in 2003 he was tournament's the leading point-scorer with 40 points, but didn't make a first-grade appearance while with the Canterbury club and left for South Sydney after that season.[2]
In the 2004 NRL season he featured as a goal-kicking winger for South Sydney in the first two rounds of the season. On debut against the Sydney Roosters he scored a second half try and kicked two goals from five attempts, in a 10-point loss.[4] The following round against the Wests Tigers he finished on the winning side courtesy of a golden point field goal by Willie Peters and scored from all four of his shots on goal, with two conversions and two penalties.[5]
