thanks JoTheKhan, but realy dont have this on my profile settings.... very strange... anyone know how can i proceed?
This is the BTC address you gave when you created your BF account. BF stated it can't be used to withdraw to, but it's the one listed in the public list of BF assets next to your shares count. It's not in the BF options any more. If you didn't label it in your wallet as BF public address there could be other options:
1) Search for backups of the BF public list - some people were keeping regular backups of it. Then search the list based on the amount of ActM shares you have. Hopefully you'll find one or few matching addresses and one of them should be yours and hopefully it's one you can sign with.
2) Another option is to contact Ukyo from Bitfunder to tell you the address. Maybe you can find him in IRC - last few weeks he's not answering much to any other kind of communication.
3) If you can't find the address or this is not an address you can sign with the only option is to ask Ken - he's the only one who can help you if options 1) and 2) doesn't work for you.