She set her personal best for the Half Marathon of 1:13:03 at the 2005 IAAF World Half Marathon Championships in Edmonton, Alberta, Canada. Her personal best in the marathon came during the Nagano Marathon in 2006, with a time of 2:29:46. Rillstone set a national record for the marathon at the 2007 IAAF World Championships in Osaka, Japan, with a time of 2:33:58, finishing in thirteenth place.