As it gives you multiple addresses I wouldn't know which one to register, right?
Cheers
There are several options to participate with a Electrum wallet:
1. register one address (from the receive tab) and transfer the complete balance of your wallet there
2. sign a message with your addresses, one at a time (you can link them all to the same byteball wallet)
3. control which address will receive the change by using the freeze/unfreeze feature of Electrum
IMHO #1 is the easiest one!
When is the snapshot? Is there a wallet for Mac or an online wallet?