format

<amp-ad
		type="adsense"
		width=320
		height=50
		data-ad-client="ca-pub-0000000000000000"
		data-ad-slot="0000000000">
</amp-ad>

you can use the code below to add it to the header.

add_action('amp_post_template_head', function () {
	?>
	<amp-ad
		type="adsense"
		width=320
		height=50
		data-ad-client="ca-pub-0000000000000000"
		data-ad-slot="0000000000">
	</amp-ad>
	<?php
});