The Edinburgh Gunners player scored six from six attempts for the Scots which, coupled with his second-half try, gave him a personal points tally of 20.
With the Calcutta Cup up for grabs at Twickenham in a fortnight, McGeechan joked: "I know how Clive Woodward feels now.
"You have to give credit to Chris for his kicking. We actually got points for all the good rugby we were playing.
"You don't always get tries but when you get penalties or conversions from the touchline it give you a tremendous fillip."
But McGeechan was less impressed with substitute referee Tony Spreadbury, who replaced injured Argentinian match official Pablo Deluca at half-time.
Wales scored two tries in the closing moments although the Scotland coach admits some of the blame should go to his side as well.
McGeechan said: "We took our foot off the pedal a bit. We wanted to score first after the break which we did. Then we eased off and Wales, who are a very good side, took advantage of it.
"Apart from the comedy act in the last five minutes it was very good. I think you have got to keep refereeing to the final whistle and not stop three minutes short."