Hints from a librarian with a Microsoft Surface Tablet on the OverDrive READ format:
The touch screen on both RT and Pro does not work with the OverDrive READ format's font settings buttons, but the keypad mouse does work to set them.
If the user did not buy a keyboard, the workaround is to use the Windows 8 browser’s charm for Internet and slide the Zoom button to change font size. This will reformat the pages of text very nicely.
Thank you, Nancy!