Chalk paint is really like any other paint, just paint it on. To protect the surface read the label to see if you need a wax topcoat.
Why would you want to use chalk paint? Regular paint would be perfect for shiplap. If you want it distressed, water down the paint slightly. If you want it to look finished, use a primer and then a paint.
Post your finished product!
Agree with Jeanette. Much cheaper to use regular paint.