Just trying to help you out, so don't take this the wrong way.

Can you sign a address proving you have the BTC you're selling?

Escrow? There really is no point in asking this as most scammers now say they accept escrow only to: Impersonate an escrow like a high ranked forum escrow, use a fake escrow website or send fake / spoofed emails pretending to be from reputable websites or ignore once the buyer or seller makes it clear enough they are not sending first.

Reason I ask the above is there has been a plague of scammers recently. This could go either way, you getting scammed or you scamming, so here are some tips you should know by now but just in case:

NOBODY should send first to you, doesn't matter if it's PayPal or Skrill and small amounts. Chargebacks are not always possible and sending first doesn't prevent one in the first place. Escrow doesn't protect you at ALL but neither does anyone sending first to you.

You should NOT send first to anyone, unless they are very reputable and can sign a message or somehow can confirm they're account has not been hacked. Even then, a reputable escrow (Localbitcoin.com if you won't trust a on site escrow) is still recommended.

I may be interested. What rates are you offering? I don't use skype so would you mind sending me a message or posting here?