I am so pleased that you referred [REFERRAL NAME] to my office.  I like to know when I am doing a good job for my clients, and referrals like yours are very encouraging. 
I enjoyed meeting [REFERRAL NAME] and I am confident that we will [MOVE (HIS/HER/THEIR) HOME QUICKLY/FIND THE PERFECT HOME FOR (HIM/HER/THEM)].  I will take special care of [HIM/HER/THEM] so that [HE/SHE/THEY] will appreciate the favor you did by sending [HIM/HER/THEM] our way! 
Client satisfaction is my primary goal.  You can feel confident that any future acquaintances you refer to me will get the very best service I can provide. 
Thanks again! 
[NAME]
[TITLE]
