Background composite picture doesn't fill render

Hi, The sky background doesn’t fill out the whole render image. Any idea what went wrong?

If the background sky is a plain image, you could scale it!

or

make the island smaller and move the camera closer.

Check your camera view before rendering!
Then as FedPete says you could scale the image used as a background.

If I understood correctly, all you need to do is put a scale node right after the image node.
image
This happens when the image you are trying to comp in is a different resolution to what you’re rendering.

Thanks everyone for providing different solutions. Tired each one and they all worked.