'72 Dart headliner board questions

Hey folks,
I'm looking to buy the board style headliner as it is what came out of my Dart. Looking at the pictures of the headliners that are for sale, the corners have slits in them. I know this is so the headliner can bow a little, but how do I make that slit look good when I install it? Will it look good on it's own? How do I make the sail panel connection look good?
Just wondering as this is my first headliner! Thanks to everyone.
Thanks FABO!

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