Use it when trying to remember someone's name by associating their face or traits. I've seen her at several meetings, but just can't put a name to her.
Pro Tip 2/3
Visual Recognition
Often used when you recognize someone visually but struggle to recall their name. That actor looks familiar, but I can't put a name to him.
Pro Tip 3/3
Partial Recall
Implies that some recognition is there, but not complete identification. She mentioned that poet I liked, but I still couldn't put a name to her.