Wide instead of square aspect ratio thumbs?

Hi. Your plugin looks great so far. However by default the thumbs appear square – and my feature images are wide aspect ratio (like a typical blog post, they are 16×9).

I can’t see in the settings or in this forum anything about using thumbs in wide aspect ratio though I know they must exist because plugins like “Recent Posts Widget With Thumbnails” use wide image thumbs in the sidebar location.

Please advise. Thank you.