The second category of fonts available in the Properties inspector is System Fonts. The System Fonts category is a list of all of the fonts that are installed on your computer not in the Web Safe fonts category. Using these fonts when developing a website (and remember that your Captivate courses are exported as mini-websites) is risky, because there is no guarantee that the fonts that are available on your computer are also available on the computer that's used to view your content.
When using a System Font, Captivate exports the Text Captions and Smart Shapes with text as images. This is the only way to make sure your text content is rendered exactly as you designed it.
When creating a Responsive Project, text is never exported as images because it is difficult to make an image truly responsive. This stresses the danger of System Fonts even more. When developing eLearning content, you definitely don't want to use System Fonts. You will learn more...