Selection Tickbox for Instant Articles on Posts

Hi,

First of all, thanks a big bunch for the FBIA integration. I really appreciate it that I can finally customise my FBIA (with your plugin template help) and need not use other extra plugins in doing so.

I wonder if it is possible to add a tickbox in post editor (which default is unticked) to only publish selected posts to the FBIA RSS?

Been stuck on this feature forever. Really appreciate it if it can be implemented.