The story of how the structure of DNA was deduced is fairly complicated and controversial, but most parties agree that a key pieces of data was "Photo 51", an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952 (or possibly other similar images taken at the time as part of the same study).
Ray Gosling, who took the photo, was a doctoral student at the time. The Wikipedia page for the photo indicates that he was supervised by Rosalind Franklin, at least for a while:
James Watson was shown the photo by Maurice Wilkins without Rosalind Franklin's approval or knowledge (although by this time Gosling had returned to the supervision of Wilkins).
One controversy in the story is that the photo was shown to Watson and Crick without Franklin's knowledge or permission, which should have been sought first as she was his supervisor.
However, this article discussing a 2015 play about the issue (called Photo 51) includes an explanation by Professor Tony North, who was also supervised by Wilkins and shared equipment with Wilkins and Franklin, that:
Wilkins had to know what Gosling was doing, as he rather than Franklin was his PhD supervisor. Franklin was ineligible for the role because she did not have a formal university position, but a personal research fellowship, Professor North said.
“The result is that Maurice had every right to know what Raymond had been doing and what results he had achieved, so that he had a right to see photo 51 without seeking Rosalind’s permission,” he said.
A quote from a primary source seems more credible. I also know from experience that other lab members often play a substantial role in training or supervising doctoral students without necessarily having a formal role in their supervision (i.e. being registered as a supervisor).
Was Rosalind Franklin, at any point, formally supervising Raymond Gosling's doctorate?