Dear Mr. Tse,
I am the father of Jonathan, whose wedding to Jessica you recently conducted at the Hong Kong Country Club. Although I shook your hand and thanked you on the day, I wanted to contact you to thank you in a slightly more formal way.
Your officiated superbly. Thanks to you, the formal ceremony went flawlessly, and your easy and friendly manner enhanced proceedings enormously.
I daresay you do this kind of thing all the time -- but to us it was a one-off; a special occasion made all the more memorable by your contribution. So, once again -- very many thanks.