Calculate magnetic field around a PCB board

Dear Mr./Ms. Comsol,

 Is there any tutorial about magnetic fields calculation around a PCB? 
 Since the concerned frequency is only several kHz, the magnetic field is still decoupled from electric field. So, I should use the "mf" physics, right?
 However, when I tried to use "mf" physics, I cannot select proper domains to be "Coil". One problem is that the copper layers in PCB are very thin, so they are "boundaries". However, some connectors outside the PCB are "domain". 
 By the way, could you clarify whether the "Coil" in comsol has to be regular one, such as cylindrical, spiral, etc.?

Thanks