<amp-ad width=300 height=168 type="yieldmo" data-ymid="1349317029731662884"> </amp-ad>
For semantics of configuration, please contact Yieldmo.
Yieldmo implicitly handles rendering different sized ads that are bid to the same placement. No additional configuration is required for the tag.
Above the fold ads do not resize, so as not to not disrupt the user experience:
Below the fold, ads resize: