How about just setting a large live trap out in front of the porch, and bait it with a fresh hunk of meat...

Cat walks in, you bag him/her up and after a few minutes drive up in the hills you let him/her go. No need for that cat to die, IF it is in fact a Bobcat.

Or, bed a 1-1/2 coil spring trap in front of the opening, and then do the above steps to release.

Saves you the fine, and of shooting a Bobcat when it's pelt is at it's worst. Hopefully it isn't a pregnant female.

Mike

p.s. Spent years running traplines in WA and doing some nuisance work as well. Never seen or heard of a Bobcat living under someones house. Have you considered that it might be a big raccoon?