If you've placed any 3D annotations before the presentation, they will appear in the model. You also have the ability to place 3D annotations during a live presentation, this is a great way to take down comments from designers and clients.
Adding Annotations During a Presentation
If your clients are in VR and you are following the presentation on your desktop, you can add annotations or notes to what they are looking at. To do so, press "Enter", enter the text and click on where you want to leave the annotation.