how to include custom html per page?

Hi

I’m trying to include custom html on some of my pages put the inner parts keep getting stripped out, more specifically im trying to add the following snippet to a bunch of blog posts:

<amp-experiment>
<script type=”application/json”>
{
“experimentName”: {
“sticky”: true,
“variants”: {
“0”: 33.4,
“1”: 33.3,
“2”: 33.3
}
}
}
</script>
</amp-experiment>

but on the pages themselves it outputs the following:

<amp-experiment class=”i-amphtml-element i-amphtml-notbuilt amp-notbuilt i-amphtml-layout-container”></amp-experiment>

Any ideas how to fix this?

Thanks!

Steve