Of your acquaintance
Definition 1 of 1
Pro Tip 1/3Personal Connection
Use when referring to someone you know directly, highlighting the personal nature of the relationship. 
I'll introduce you to an artist of your acquaintance to discuss the gallery.
Pro Tip 2/3Not Acquaintances
Do not use for people you've merely heard of or seen online but haven't interacted with personally. 
Celebrities I admire aren't people of my acquaintance since we've never met.
Pro Tip 3/3Formal Contexts
Fits best in formal or semi-formal conversations, as it may sound overly formal in casual settings. 
Is there a scholar of your acquaintance who could speak at our conference?