Created Custom Fieldtype and display on form

I’ve trying to customize the “opportunity” form. At first, I tried to update the “lost reason” for unfortunately that did not work. So I went ahead and created another fieldtype that I’d like to be display based on the response from the “lost reason” field.

However the fieldtype is not even showing up on the form(GUI).

Is there something that I am missing?

Thanks for any help you can provide!.