How to designate a thumbnail image

Thumbnail images are designated as follows:

<media:thumbnail url="https://times.smartnews.com/2014/06/16/sanfrancisco/img.png" />

If the issue remains unresolved, the cause may be one or more of the following:

Cause

• The image size is too small: Setting images of 1,500 px or more is recommended.
• The image data size is too large: We recommend images of 1 MB or less.