Foster called the meeting a rare appearance by Tutu.
"He's not seen very often in public so this was a historic piece of video in two senses," Foster said.
They also shared a photo of the archbishop blessing Archie with a kiss on the head.
The meeting happened at Tutu's foundation in Cape Town. The foundation helps lead the discussions of social justice and human purposes and is an outlet for the development of youth and leadership in South Africa.
It also is an outlet to spread Tutu's teachings to future generations.
During the meeting, Prince Harry shared that his son "constantly wants to stand," People magazine reported.
Those who have talked to the royal family said Meghan shared with them that "Archie is the most calm, beautiful, easy baby," Nazli Edross-Fakier told CNN. But Edross-Fakier said Prince Harry added, "He's come alive. He's shouting and screaming and carrying on."
Edross-Fakier met the duke and duchess as they visited her sister's home in the city's Bo-Kaap neighborhood on Tuesday.
"They were like two normal people that came into our home. There was nothing ostentatious or pretentious about them and I think they were just happy to be sitting down, taking a breather from all the people and the cameras." Edross-Fakier told CNN. "It was like having friends over for tea."
Meanwhile, Archie's first official trip isn't the only milestone making news during the royal tour.
The Duchess of Sussex spoke about her roles during a stop in Cape Town's Nyanga township where she talked about her heritage, People magazine reported.
"On one personal note, may I just say that while I am here with my husband as a member of the royal family, I want you to know that for me, I am here as a mother, as a wife, as a woman, as a woman of color, and as your sister," she said. "I am here with you, and I am here for you."
She told the women of the district to fight for "respect, dignity and equality" after she got to see girls taking a class in self-defense, People magazine reported.