With the Scots trailing the Glasgow man took a pass from Mike Blair to go in at the posts to grab the win.
Richie Gray was credited with Scotland's first try while Greig Laidlaw added the other points with the boot.
With victories over Australia, Fiji and Samoa, and the introduction of several new caps, including Glasgow's Ryan Grant, Tom Ryder and Robert Harley, the Scots can look forward to the new season with optimism.