Set specific a .php template to specific page

Hi Guys,

I have to include a advanced form that someone else made.
I did look for a plugin, so that i can include a .php file in the page’s content but with no luck.

I though if i can set a specific template to that page, then it is fixed.
So i want (for example) page: “Order now” take the template ordernow.php instead of page.php.

Is that possible? I did search in the docs, but couldn’t find anything about it.

Thanks for all help!