Rantanen ya ci gaba da ci gaba a cikin tawagar matasa na Finnish ta hanyar samun zabin zuwa gasar zakarun Turai.
Gasar Zakarun Duniya ta 2015 a Toronto. Duk da rashin nasarar da aka samu a matsayi na bakwai, Rantanen ya ba da gudummawa tare da kwallaye hudu a wasanni biyar don samun dan wasa na uku a cikin zabin tawagar.