Will PG use composite index to enforce foreign keys?

Hi -

I know that the foreign key machinery will use an index on the
referring column if one exists. My question is whether it will use a
composite index? For instance:

create table allLemmaSenseMap (
wordID integer references allLemmas,
senseID integer references allSenses,
primary key (wordID, senseID)
);

If I delete something from allLemmas, will the FK check use the PK
index above? (I know I should at least have an index on senseID as
well, because of the other foreign key.)

As a secondary question, is there any way I could have answered this
myself, using analyze, the system catalogs, etc? ANALYZE DELETE
doesn't seem to show the FK checking that must go on behind the scenes.

Thanks.

- John D. Burger
MITRE