How do I allow execution of PHP scripts in HTML files?

The following shall be added into .htaccess file:
AddType application/x-httpd-php .php .htm .html .phtml

* Note: to enable this function operation at certain servers it shall be necessary to also send a request to support@r01.ru.

* Note: when working in PHP in FastCGI/CGI mode it shall be necessary to send a request to support@r01.ru.