add an external md file to a php page

… and, of course see it as html, with the same graphical appearance of any other web text.

A way can be use a very light javascript, md-block.js, di Lea Verou.

Then you can add a function to your php website, like the following:

<?php
/* to call a file Markdown from a given folder */

function scheda_md($file)
{
    global $yourwebsite;

    $file = basename($file);

    return '<md-block src="' .
           $yourwebsite .
           '/the-path/where-are-md-files/from-yourwebsite-root' .
           htmlspecialchars($file, ENT_QUOTES, 'UTF-8') .
           '"></md-block>';
}
?>

And in the page where you want to show that md file you can use this code:

<?= scheda_md('the-md-name.md') ?>