The Staggies secured deals for Dutch wingers Darren Maatsen and Melvin De Leeuw earlier this summer and they have swooped for more new recruits from Holland.
Luckassen, who has represented Holland at Under-19 level, will add more firepower to Derek Adams' squad, while the County boss hopes Klok will supply a physical presence.
"Kevin is a talented player who has come through the AZ youth system. He is a strong and powerful attacker," said Adams.
"Marc is a 20-year-old central midfielder. He is a competitive ball winning footballer and will add another dimension to our squad."
County are expected to announce another signing on Thursday with former Chelsea defender Ben Gordon set to join on a one-year deal.
Gordon was released by Chelsea on the final day of the January transfer window and the 22-year-old has been without a club since a month-long spell at Yeovil Town.
The left-back has previously played north of the border during loan spells with Kilmarnock and made 21 appearances in his first sixth-month stint at Rugby Park in 2010.
The former Leeds youngster was also dispatched to Tranmere, Scunthorpe, Peterborough and Birmingham by Chelsea during a six-year stay with the Blues after leaving Elland Road in 2007.
He returned to Kilmarnock in January 2012 and made a further 20 appearances, including a starting role in the Scottish Communities League Cup final success over Celtic at Hampden.