If you want to allow php code processing in files of different format, you have two options to do that:
1) Modifying httpd.conf to allow this for all projects on your server, by adding:
AddHandler application/x-httpd-php .htm .html
2) Creating .htaccess file in your separate project top directory with:
<Files />
AddType application/x-httpd-php .html
</Files>
For second option you need to allow use of .htaccess files in your httpd.conf, by adding the following settings:
AllowOverride All
AccessFileName .htaccess
1) Modifying httpd.conf to allow this for all projects on your server, by adding:
AddHandler application/x-httpd-php .htm .html
2) Creating .htaccess file in your separate project top directory with:
<Files />
AddType application/x-httpd-php .html
</Files>
For second option you need to allow use of .htaccess files in your httpd.conf, by adding the following settings:
AllowOverride All
AccessFileName .htaccess