Hi there!
You just need to create your bitmap font file and attach it to a plugin parameter.
Can you show me a screenshot of your plugin parameters?
Your font file must have the same amount- and the same order- of characters listed on the plugin parameter "all characters".
So if you created a new PNG to be a bitmap font, it needs to follow that rule above.
You can take the default one that is on the sample project as an example of how to create your PNG(BITMAP) font file.