Khan is especially pleased to see Singh making progress, having overseen the 20-year-old's development at his Stars of Africa Academy.
Singh, who has attracted interest from Real Madrid in the past, recently penned a new five-year contract with Braga after impressing for the club's reserve team, scoring 11 goals in 35 appearances in all competitions.
Braga finished fourth in the Portuguese topflight in 2017/18 behind champions FC Porto, Benfica and Sporting Lisbon, and will vie for Europa League qualification in July.
"I think playing with Braga will assist him [Singh] with going to the next level as far as football maturity is concerned. He's very quick and skilful," Khan tells KickOff.com.
"South Africa has got many top players now with the likes of Phakamani Mahlambi, with Bongani Zungu in France, Keagan Dolly. We have got good players out there, so Luther will have to work hard to get his place [in Bafana Bafana].
"I said to him it's not going to come easy, you are young, you have got age on your side and you are the future. You are not going to be playing right now, but just be patient, work hard and you'll get your chance.
"Without doubt he'll make his mark in South African football under the current or next coach ... He'll make his mark."
Meanwhile, Khan defended Singh over his failed attempt from the spot in the penalties shootout loss to Madagascar in the COSAFA Cup quarter-finals in Polokwane on June 3. Singh endured criticism afterwards on social media platforms.
"I think some people have small minds and forget that players like Roberto Baggio [in the 1994 World Cup] and some of the greatest players have missed penalties in the past," the SuperSport TV pundit points out.
"It's not a case of missing a penalty that will determine whether you are going to be a top player; it's how you perform consistently."
He adds: "It's not like he took the penalty casually as has been claimed.
"Unfortunately the goalkeeper that he was playing against is not a top goalkeeper. In other words he didn't move.
"A good goalkeeper like Itu Khune will decide early where to go because even the one he was beaten with he was late to them. Good goalkeepers choose the corners early and that is why they save them.
"He took penalties like that against Porto and he scored against top keepers.
"So this is where the ignorance of our public comes in to play and people in general. They just look at the miss, they don't look at how the penalty was taken, and yes on another day it can be a brilliant penalty."