On behalf of (Collaborator/Extension), I would like
to thank you for your informative presentation on (title of talk)
at the Retirement Planning Education Program on (date).
We are fortunate to have had someone of your professional
expertise and credentials volunteer time from your busy schedule
to address the participants and serve as a resource person. (Add
personalized comment as appropriate)
It has been a pleasure working with you, and I look
forward to working with you in future educational endeavors.