i can insert html to all pages via Apache, but only for site that hosted by my apache, not all site though my apache proxy server.
this is how it work. i set up an XAMPP, download mod_layout 5.1 for apache 2.4. (install mod_layout is simple, if you use XAMPP for windows, just download mod_layout.so 5.1 for windows and put it to your apache module folder $home/apache/module, then add the config DSO to your httpd.conf LoadModule layout_module modules/mod_layout.so - if you using linux or other os, you should download mod_layout.so for linux, then run make command to install)
After install mod_layout.so for windows, just put this code on your .htaccess file or httpd.conf your will get html insert to all your page:
<IfModule mod_layout.c>
AddOutputFilter LAYOUT html
AddOutputFilter LAYOUT htm
AddOutputFilter LAYOUT shtml
AddOutputFilter LAYOUT shtm
AddOutputFilter LAYOUT cgi
AddOutputFilter LAYOUT php
LayoutFooter "C:/xampp/apache/cgi-bin/footer.php"
</IfModule>
C:/xampp/apache/cgi-bin/footer.php is where you put your html or php file, in my situation is C:/xampp/apache/cgi-bin/footer.php, but you can put it any where, just give the right path, you'll be fine