Papua New Guinea finished second with seven points as Hong Kong came third with five points two ahead of fourth placed Uganda.
Douglas, Canada's all-time try leader, had missed the two previous stops due to a concussion.
Rodrigo Freudenthal and Rodrigo Marta had tries for the invitational Portuguese side.
The Blitzboks won 21-7, after leading 7-0 at the break.
Norton, who leads the circuit with 324 career tries, broke the record set by Collins Injera of Kenya at the 2017 tournament.
Nipsey Hussle to have massive memorial at Staples Center
Kapri, continued: "I ain't trying to shoot (my shot) at her ..." "She might need a whole year to be crying and s***". Holder is now being held without bail and could face a life sentence if convicted, according to a Billboard report.
Australia are licking their wounds after losing 40-19 to New Zealand in their opening match of the "Pool of Death", with Fiji and Kenya their opponents on Saturday. The United States, which leads Rugby Sevens league, is first in the group after beating Spain 36-7.
In the other pool match, it was a repeat of last year's final, with Fiji beating Kenya 22-5.
New Zealand ended up comfortably winning the match, with Joe Webber marking his return from a year out by scoring the last of their six tries, and Sam Dickson, Joseva Ravouvou (2), Regan Ware and Jona Nareki also crossing.
South Africa, who went through Pool "A" unscathed, beating Japan 22-7, Scotland 26-10 and Samoa 21-7, face US in the Cup quarterfinals.
Scotland's rugby-playing women, assisted by three from the Borders, have reached the quarter-finals of a sevens tournament in the Far East.