Determining the dots (signs) in a planar transformer

Hi all,
Can someone tell me how can I determine the dots (i.e how the current flows) in the primary an secondary coils of a planar transformer? Is there a safe way to figure them out or I need to use EM simulation?

Thanks

It's the same as with any transformer. Two windings with equal polarity have equal voltage sign and opposite current sign. As given by elementary electromagnetic rules.