Check pages 12 and 98 in the WDFW fishing regs and be able to document when and where your Canadian fish were taken. Combining Canadian and US harvest can get dicey if you are in possession, in the field, of more than 2 fish. I wouldn't be fishing both jurisdictions on the same trip/day without landing one or the other first.
From my read, if you are going to claim Canadian fish you should give serious thought to meeting their transport requirements. No telling which agency you might run into on the water or on land - DFO, USCG, WDFW, Clallam County, USFWS, NOAA....all have jurisdiction at one or more locations along your route.
If you get stopped in WA and are claiming Canadian halibut, you have to be able to prove size and species pursuant to the Canadian rules.
Fishers are reminded that it is a violation to have
any fish in your possession that is caught while
recreationally fishing that has been skinned, cut,
packed or otherwise dealt with in such a manner
that the species, number, and length of the fish
cannot be readily determined.
Regulations require that where size limits apply to any
fish caught while fishing recreationally, it must remain
in a condition that the size of the fish may be readily
measured. Possession of fish that are not readily
measurable, if inspected by a fishery officer
constitutes a violation of the regulation.
If fishing out of Neah Bay, don't forget about the Canadian closures and depending on where you are fishing, you might need the paper license. The electronic license won't suffice.