Placing text comments to mark up your blueprints is a simple way to add context. Placing a comment can be done by just clicking, this will result in the default box size and text, or you click and drag out the size of the box. Changing the contents on the comment is done under Text in category.
Auto Font Sizing
To get the text size to scale automatically to the size of the textbox you enter ‘0 pt’ font size under properties. This will cause the text to take up all space in the box and scale itself to the bounds of the box.