The online example is accessible here
I am sharing here a simple snipped showing how to add page numbers into a report based on wkhtmltopdf recipe. It is a bit more complicated than in phantom-pdf recipe, but the result is the same.
The page number and other information are passed into the header's window.location.search variable by wkhtmltopdf. You just need to pick it up with javascript and place it anywhere you want.
Put the following into the wkhtmltopdf.header and see the output.
<!DOCTYPE html>
<html>
<head></head>
<body>
Page <span id='page'></span> of
<span id='topage'></span>
<script>
var vars={};
var x=window.location.search.substring(1).split('&');
for (var i in x) {
var z=x[i].split('=',2);
vars[z[0]] = unescape(z[1]);
}
document.getElementById('page').innerHTML = vars.page;
document.getElementById('topage').innerHTML = vars.topage;
</script>
</body>
</html>