In my projects I use a variable to work the text contents in vector format, so I can see the output result better.
But what can I do to get captivate to install this font on the end-user machine?
Captivate will never install something on another machine, that would also be breacking many laws.
You cannot embed fonts out of the box. If you are working with non-responsive projects, and non-dynamic text containers (which don't include variables), it will not be necessary because the text will be converted to image.
That is why I asked the question, I am working with texts included in variable fields to improve the definition of texts.
I am a bit confused by the terminology you are using. By 'variable' fields, do you mean text containers (shapes or captions) with one or more embedded variables ($$var$$)?
In that case, since they need to be rendered on runtime you should only use Websafe or Adobe fonts.