Display WordPress plugin after the header

I'm developing a plugin for WordPress. My plugin contains a form. I would like to display this form in certain pages after the header, but I'm unable to achieve this.

This is how I displayed the form until now. It shows the form on every site at the top, which is not what I want.

function pre_display_form() {
     include("form.php");
}
add_action("init", "pre_display_form");

I was experimenting with add_action and add_filter, but unsuccessfully. I'm not able to find the right hook.

I know there must be a way to do it. Can anyone help me ?

via Chebli Mohamed