FreePDF: The Rise function is possible in FreePDF only for newly inserted text boxes.
You can add a superscript (for example, r2) or a subscript (for example, H2O) by applying the commands 
on the ribbon tab Home | group Character. For more information, see Superscripts and subscripts.
In addition, the command Rise can be used to set the exact vertical position for the text.
To do so, proceed as follows:
| 1. | Select the Text edit tool  in the Quick access toolbar. |
| 2. | Select the text that you want to fit. |
| 3. | Choose the ribbon command Home | group Character | Spacing and scaling  , and select Rise in the menu that appears. |
| 4. | In the following dialog box Text Rise, enter the desired value. |
| When you enter positive values, the text is raised, and it is placed below its baseline if negative values are entered. |
If necessary, you can resize the text by applying a different font size to the selected text on the ribbon tab Home | group Character.