I have WordPress 3.5.
I want to display the thumbnail 150x150 pixel, but when I have the value of "thumbnail" in "Post's thumbnail custom field name" it comes back with the full 620x350 pixel image.
Not sure what to do.
If you have WordPress version 2.9 or higher, you can use built-in thumbnails support - RSS Manager will fetch them automatically.
How exactly do I take advantage of the built-in thumbnail support? Am I to do anything besides enter "thumbnail"?