Panel interview thank you

I just had a panel interview with 4 people for a residency program. I told myself I was going to remember to ask for names and contact info, but got nervous and forgot. At the end of the interview, they said to direct any questions through the HR recruiter, since she'll be the one contacting applicants to say if they were accepted or not. What should I do about a thank you? I can't even remember all the interviewer's names. I think the residency interview panel changes daily according to who is available. Should I just send a thank you to the HR recruiter who set it up for me? It seemed like the interviewers didn't want us contacting them. Panel thank you's stress me out :)