That won't work because OneDrive doesn't share the files the way an image board like Imgur does. You also need to use the correct syntax (which is automatically generated by Imgur):
Use Direct Link with the Insert/edit tool and you can manually resize the image to fit, or use either of the BBC tools to paste directly in the text box.
You can also use the forum's Preview button to make sure the image is sized properly, and you can drag a corner and resize the image if needed.