Hi Richard Tilford,
If you are using Adobe Reader, then its not possible to add these tools to the toolbar using the same.
However, you can add 'Draw free form' and 'Erase drawing' tools in the toolbar using Adobe Acrobat.
You might right click anywhere on the toolbar and choose Customize Quick Tools option.
From the dialog box that opens, choose Comment and then add both the tools. Click on 'Add to Toolbar' option and choose Save.
Regards,
Anubha