include in templates?

[idnpros]

hi, i need to include a php file in a postbit template, how do i do it, i tried using the common php include function but doesn't work, then i search the forum and found something about:

ob_start();
include('http://site.com/file.php');
$variable = ob_get_contents();
ob_end_clean();

but doesn't work too (or i am putting something wrong)

pls help me, thanks in advance