 Less than a year after leaving high school at Wellington's Scots College, Riddle shot to prominence after a high-scoring debut season with Wellington United in the New Zealand Superclub competition.At the age of 19, Riddle was the youngest member of Bobby Clark's 1996 New Zealand Olympic Team where he made four appearances including one as a substitute in a 1–0 victory over then Oceania rivals Australia where ex-Fulham midfielder Simon Elliott scored the only goal of the game at Adelaide's Hindmarsh Stadium.After brief stints with several clubs including Chelmsford City in the UK, Riddle turned to the US college system and spent two years with the Myrtle Beach-based Coastal Carolina University before being signed by Kiwi football icon Wynton Rufer for the Kingz debut season in the National Soccer League in 1999.