De or het projectreferentie?

The correct Dutch article is:

de projectreferentie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use projectreferentie

the projectreferentiede projectreferentie
this projectreferentiedeze projectreferentie
that projectreferentiedie projectreferentie
our projectreferentieonze projectreferentie
your projectreferentiejouw projectreferentie
every projectreferentieelke projectreferentie
which projectreferentie?welke projectreferentie?
a big projectreferentie / the big projectreferentieeen grote projectreferentie, de grote projectreferentie