Question:

How can I annotate my profile in the profile view?

Answer:

In the Profile View, the option to annotate the model or the element is located on the HUD as seen below.

The option to annotate the profile element is also available by selecting and hovering over the profile element.

The annotations are not selectable. The size of the annotations can be adjusted using the Annotation Scale, and the Transparency can be adjusted in the File > Settings > User > Preferences > View Options - Civil.