South Africa finished as runners-up at the HSBC SVNS Vancouver leg after going down 19-12 to Argentina in the final.
The South African men had reached the final with a 12-10 victory over Fiji in the semi-finals after scoring the winning points in the final play of the match.
South Africa have now finished fifth in Dubai, won in Cape Town, placed fourth in Perth and taken silver in Vancouver, which leave them six points shy of log leaders, Argentina.
The South Americans (68 points), Spain (64 points), South Africa and Fiji (both on 62 points) are moving clear from the rest of the pack, with a gap opening between the top four and France (46 points), Australia and New Zealand (38 points) after four tournaments played.
Hong Kong in a month’s time and Singapore are the two remaining tournaments left in the regular season, before the Grand Finale in Los Angeles.
The Pumas laid the foundation of their victory in the final before the break, scoring the only two tries of the half. South Africa were penalised a couple of times at the breakdown and could not get any momentum, while Argentina were more clinical when in possession and they deserved their 12-0 lead.
When Argentina scored in the opening play from the second half restart to take a 19-0 lead, things looked dire for the men in green and gold.
A brilliant 80m solo run by Quewin Nortje got them on the board and going. When Siviwe Soyizwapi scored his 154th career try from a move he initiated, South Africa were just a score away from levelling matters.
Spain finished third after beating Fiji in the playoff for bronze.
