Kim played a six-hole stretch in six under with four birdies and the eagle on the par-5 seventh. The South Korean had only 24 putts as she tries to build on a third-place finish last week in the CPKC Women's Open.
"I feel like this course is a little softer, greens are a little softer than last year," Kim said. "That's why I was able to get a lot of birdie chances, even front nine."
Kim, a former world No.2 and 2020 Women's PGA Champion victor, broke a five-year winless drought last October when she captured the BMW Ladies Championship in her home country.
Miyu Yamashita, the runaway winner Sunday in Edmonton, Alberta, was a stroke back along with Emily Kristine Pedersen.
After tying the LPGA Tour's 72-hole scoring record in her nine-stroke victory in Canada, Yamashita led the field with 10 birdies, but had a double bogey on the par-3 eighth. The Japanese star played the back nine in 30 with seven birdies in eight holes. She also had just 24 putts.
"Today putting, middle putting," Yamashita said. "So good."
Somi Lee opened with a 66.
Top-ranked Nelly Korda and world No. 2 Jeeno Thitikul of Thailand both shot 72 in the final event before the Solheim Cup. All 10 players atop the women's ranking are in the field.
Karis Davidson (70) is the leading Australian at two under, while compatriots Grace Kim and Cassie Porter both shot 72.
The $4.4 million ($A6m) purse is the largest outside of the majors on the LPGA Tour.
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