In the videos on StitchArtist L1, you see that the Windows version shows a preview of what the test will look like with a particular font. This is also true on the Mac - if yours is not showing the text in the selected font, all you need to do is make the dialog box bigger.
You can also use the gear in the upper left corner to turn the preview on and off.
You can also use the gear in the upper left corner to turn the preview on and off.