No seriously, I think what is meant by selling internationally is listing on an International site.

If that's what you have done and not signed, then you are special.

If you have never quoted overseas postage before then you get it when you try to list on your home site.

I have never had to sign it using my well established id but for a new to selling id I had to do the sell your item form listing first, it was driving me crazy trying in TL so I just called ebay and they told me to do the first one with overseas postage and then update and synchronize TL and all would be well and yea all was well