XF 2.1 How to filter, modify output headers for Content-Security-Policy?

[dazamate]

Hey guys.

I need to be able to add this to my xenforo headers...

header( 'Content-Security-Policy: frame-ancestors https://*.mywebstie.com' );

I tried using htaccess, it isn't working and I suspect it is being overridden with php inside of xf.

I am good with php but I am not good with xf plugins.

Could anybody provide some help with this. Thank you.