The rule is:
-------------------
( 7 ). Sig dimensions will now be 550x125, and the file size will be, at a maximum, 100kb.
-------------------
Now, I don't care if you have 1 sig that's 550x125 or 18 sigs that total those dimensions. Stay within the 550x125/100KB limitations and all will be well.
Is that blatantly obvious to everyone? Good. And newt, if you weren't aware, you have two sigs too. Combined, they total 666x129. So, YOU get rid of one of your sigs.