Reid, 29, sank five birdies and also eagled the fifth to move to 15 under overall after the third round.
United States' Angel Yin and Australia's Su-Hyun Oh are tied for second on 13 under.
England's Holly Clyburn shot a 72 to move to 11 under and compatriot Florentyna Parker is a stroke behind.
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Veteran Laura Davies, who equalled the course record with a 65 in the opening round but followed it with a 76 to slip out of contention, is nine shots off the lead after a 73 in her third round.
England's Melissa Reid carded a six-under-par 67 to take a two-shot lead going into the final round of the Oates Vic Open in Victoria, Australia.