A compression check will identify whether it's the rings or the head, if you do it dry, then wet. Do a normal comp check in that cylinder, then add a few squirts of oil from an oil can into the spark plug hole, and check the compression again. If the numbers go up significantly, you have a ring problem. If they don't, it's the head. A leak down test will then specify where in the head the problem is.
Take care,
~Chris
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