Bing Tag Manager

Im looking to add the below code for Bing tag manager but am unsure. V4.52

I thought it was to be placed in meta.tp but seems not, can anyone tell me where it should go please.

And this in the tag or footer please:

<iframe src=https://www.googletagmanager.com/ns.html?id=GTM-K123

height="0" width="0" style="display:none;visibility:hidden">

if you are not familiar with addons and hooks, edit the following file

design/themes/responsive/templates/index.tpl

Do not forget to wrap your code with

{literal}
    ... your code here....
{/literal}

Thanks Ecomlabs

would I then be able to see it via View source of page as I dont see it?

Have you cleared the cache? After the changes are applied, try to delete the var/cache directory manually