As your M3 is not an SLR (unless it's a lot different than my M3!) you'll have to remove the filter to look through it to get the rotation right. I recall that years ago some polarizers had numerical scales or marks around one part of the filter and an index point on the other so you could adjust, note the proper number or mark, then put the filter back on and then set the filter appropriately. As there's no meter in your camera, no need to worry about linear vs circular IMHO.