Use whatever you like..no problem..
Dutch photos can be gotten from the team sites:
http://www.honkbalsite.com/hoofdklasse/
Just click the team name and that'll bring up the page with that teams roster and link to their website.
The neptunus have png photos...keep those as png 170x255 for best results.
Het team - Neptunus hoofdklasse - Neptunus.
Here's a sample. Jorian van Acker and Stijn van der Meer (smaller, but most are the large like Jorian).