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 2 successful years with the Myrtle Beach based Coastal Carolina University before being snapped up by Kiwi football icon Wynton Rufer for the Football Kingz debut season in the National Soccer League in 1999.
Although he signed a 2 year contract Riddle struggled to regularly feature in the Kingz side and only managed 9 appearances with a return of 2 goals both of which came away from home against Adelaide United and Brisbane Strikers.
Better form would be found in the lower United States leagues with Riddle being a mainstay of the Laurie Calloway coached Des Moines Menace side that would achieve an undeafeated season in the 2002 USL Premier Development League competition.
Riddle turned to the UK again in the hope of being signed by a Football League side but again struggled with the higher level of play and had short spells at Oxford City and Greenock Morton before being re-united with former Kingz teammates Marcus Stergiopoulos and Levent Osman at the Melbourne based Altona Magic in the Victorian Premier League.
Despite a good scoring record he fell out of favour with the management of the Macedonian flavoured club and returned to the United States.
In 2006 he became the first New Zealander to coach in the United Soccer Leagues when he accepted a player-coaching job with Kalamazoo Kingdom in the USL Premier Development League, United States elite development league.
In 2008 he served as the head coach for the Kalamazoo Outrage in the USL Premier Development League, United States elite development league team in the franchises inaugural year. On July 13th 2008 the Kalamazoo Outrage qualified for the 2008 USL Premier Development League play offs in their inaugural year.
Riddle guided his side to 2nd place in the Central Conferences Midwest Division narrowly finishing behind the Chicago Fire Premier in the regular season standings. His side would get their revenge eliminating the Chicago Fire Premier from the 2008 play offs by virtue of a 2-0 victory at Toyota Park on July 22nd.
Their fairy tale run would continue under Riddle and they defeated perennial USL Premier Development League powerhouse the Michigan Bucks on July 26th to advance to the national quarter finals where the Thunder Bay Chill would end the Outrage's season.