The people closest to us know. People who aren't, generally remain clueless.
There was one interesting dinner, where someone got offended that he ordered for me. I was intrigued and curious how he would handle it-so I kept my mouth shut (but admit to having an eyebrow raised). He basically managed it with telling them that this was OUR relationship and how we choose to manage ordering our food wasn't warranting of their time or attention.
Another time, we had a waitress who was hell bent on getting me to respond. She continuously aimed her questions at me and ignored him. It became necessary for me to tell her that it was my preference for him to place the order. She was royally offended.
A male waiter was bemused. He asked me, I deferred to Dh (with my eyes and a smile). DH ordered, the waiter double checked with me "that works for you?" DH smiled at me and gave me the signal to respond, so I did, telling the waiter with a smile that "yes, yes it does". He nodded and went to put in our order with a smug sort of look. But, he referenced all further questions to my husband the rest of the evening.
Mostly though, people don't notice. I also sit on a specified side of him-even if we are in a group of people, and I always sit beside him, not across from him.
I'm not really shy about any of those "viewable" D/s things.
However, we do have an agreement that all bedroom activities remain mine to share or not share about. Meaning-he does not have the privilege of telling other people about anything regarding our D/s behavior that isn't public behavior.