I only see one row of toolbar buttons, and some are missing!
By default, Annotum (and WordPress generally) only show a single-row toolbar in the editor. To display a second row, in particular the buttons for:
- Insert Table
- Insert Reference
- Insert Equation
Simply click the “show/hide kitchen sink” button (fourth from left) as shown here:
This will display the second toolbar button, as shown in the example below: