Create checkBox and textBox using RML

I'm trying to create a checkBox and textBox using reportlab plus. I've read their documentation but I can't seem to make it work. I keep getting an error saying that it doesn't allow the element in it's location. I've tried putting checkBoxes under all aspects of the document. There doesn't seem to be a lot of questions on here about RML either...

Can somebody show me the RML structure for creating checkBoxes and textBoxes?