Hi, i'm trying to find out the rules re using an Amex PP companion voucher for an open jaw return and the max distance between arrival and return airports? Will be flying ex UK but thinking of outbound to NRT and return from SFO (BA metal).

Sorry if this is already covered (I couldn't see the answer from the spending avios sticky thing (in the companion voucher section)).

Many thanks in advance, and may I also say what a fantastic resource this is! :-:s all round!