From this dialog box, you can set all aspects of fonts for currently selected text objects.

You can choose :

Font face, Size, Style, Strikeout, Underline and Font Colour

As you make your choices, you will see them reflected in the Sample text window.

You can choose from any font installed in your computer.

(Note that if you are creating Oak Draw files intended for use on other computers, you should choose fonts likely to be available on those computers)