> Citation needed.
There aren't any, I searched the last time the "Feynman Technique" was posted on HN and found that the term originated on Youtube [0] in 2011.
When challenged by a commenter for a source the Youtuber stated:
> The technique is inspired by Feynman, not used directly by him.
> I was inspired by the story I shared in the beginning to formulate
> his more informal approach into a method. You can see him talk
> about understanding the math ideas in his book "Surely You Must Be
> Joking, Mr. Feynman"
From there it appears that "inspired by" has transformed into "created by"