Knicks rookie RJ Barrett finished summer league in July with a flourish following a horrendous start and hopes he will carry that improvement over.

However, it won’t be with Team Canada at the World Cup in China. Though his father, Rowan, is the general manager of Team Canada, Barrett elected to show up for the Aug. 4 start of training camp and participated in a few days of drills before leaving the workouts in Toronto. With Canada flying to Australia for exhibitions, Barrett stayed behind, citing a slightly strained calf.

That decision gave Barrett the opportunity to attend the NBA’s annual rookie orientation/photo shoot in Teaneck, N.J., along with fellow Knicks rookie Ignas Brazdeikis, the team’s second-round pick. Brazdeikis, a Canadian citizen who was born in Lithuania, was not invited to Team Canada’s camp.

In his Las Vegas Summer League finale in mid-July, Barrett posted 21 points, 10 assists and eight rebounds after he had double-doubles in each of his previous two games. Still, he finished with a shooting percentage of .338 in the five games and shot just 24 percent from beyond the 3-point arc. But the No. 3-overall pick said he has been working on other shortcomings that showed up in Vegas.

“I missed way too many layups [in summer league],” Barrett told reporters in Teaneck.

However, he said he liked how he finished the tournament.

“I felt like that really got my mojo going,’’ Barrett said Sunday. “So just trying to bring that into training camp is going to be good.”

Barrett said he was happy about the Knicks’ free-agent signings of young veterans, even if none is considered to be star quality.

“It’s going to be great,’’ Barrett said. “I need that — just trying to learn the game as quickly as possible.’’

Most Las Vegas sportsbooks have put the Knicks’ Over/Under for wins at 28. Brazdeikis, the cocky swingman who looked better than Barrett in Vegas, believes the roster is solid.

“I think we got a great team,” Brazdeikis said. “I think we all have that same mentality that we just want to win and make New York proud. I think we’ll be great. We’ll work together really well.”

The Knicks will bring undrafted Mississippi State guard Lamar Peters to training camp on a non-guaranteed deal. He could wind up with G-League Westchester.