You can sign a player at the minimum and for only one month as your 13th player if you are at the cap.

As far as I see, there are a few teams that only have 10 players right now.

Try to round out your rosters, or you will end up with the available players from your chosen NBA team at the minimum to fill out your roster.

NBADan and Little General only have 10 players from what I see.

(Please tell me if I am wrong).