Missing a number of experienced players, including captain Simone Magill, Laura Rafferty and Nadene Caldwell, McArdle handed a debut to defender Jane McMaster and first caps to Kess Elmore and Charlotte Havern off the bench.
McMaster responded well after giving away the early penalty for Encarnacao’s opener, while Kelmore was lively in the second half and, at 16, it was a big moment for Cliftonville’s Havern to be introduced with 10 minutes remaining.
“It’s fundamental, especially for our younger players, to get this exposure,” McArdle added.
“It’s a risk and it’s brave, but it’s one that will definitely 100% stand strong with us in the long term.
“It will give us that sustainable opportunity to qualify for tournaments in the longer run because we need our younger players to get this exposure, but also for a lot of our senior players as well.”
After impressing in the second half before Pinto’s goal took the wind out of their sails, McArdle said his players will “hurt for the next 24 hours or so” but regroup for the second leg.
Northern Ireland will be without Chambers, who was sent off in the closing stages for grabbing the hair of Carolina Correia.
“There’s the travel over to Portugal thrown in to allow us to relax a wee bit afterwards.
“But once we get there, we’ll look forward to Tuesday again.
“We’re trying to qualify, but there is a longer process as well that we’ll use Tuesday night for.”