Example of using Imagick::setPointSize
<?php
/* Create new imagick object */
$im = new Imagick();
/* Set the font for the object */
$im->setFont("example.ttf");
/* Set the point size */
$im->setPointSize(12);
/* Create new caption */
$im->newPseudoImage(100, 100, "caption:Hello");
/* Do something with the image */
?>