Callout
With the Callout tool you can add text comment with an arrow to point to the specific spot on the page, so that readers turn their attention to this place.
Using callout
Click the Callout button 
on the toolbar or use the Comments > Callout menu item to select the Callout tool.
Next, click any place on the page you want to be pointed out and drag the comment to any location of the document where text needs to be added.
A user can modify the Callout parameters using Object Inspector. You can change the properties shown below:
- Text format, including font (name, style, size) and alignment.
- Border line style, width and color, including background color.
- Arrow size and style.
To change the location of the Callout text after adding it, you need to enable the Show move grip while editing the Callout comment.
Editing Callout text
To edit Callout comments, use the Hand tool button 
on the toolbar or press Alt+6. Next, click the Callout comment to select it. Now, you can edit the Callout text, while the comment parameters can be modified in the Object Inspector panel.
Click the Callout object with the Edit Document tool
to change the text of the callout, its position, visibility, or status. You can also enable the Locked option so that the Callout object can only be modified by its author.
More like this:
Creating and Modifying Interactive PDF Forms
Editing Vector Images
Headers and Footers for PDFs