Number of players in a team

You can specify how many players apppear in a team by editing the team, to do so Club Database > Teams > 1XI (if your 1st team is called 1XI).  Under the team setup you can configure how many players make up a team, and how many reserves, it's up to you how many you choose.   By default for most sports this is set to 11 and 2 reserves, for a team with 11 members, to allow 16 selections just change the reserves to 5.  

You can also decide whether to identify reserves or not on this page, if this is set, a line will be drawn on the teamsheet after the 11 players (if you have set 11 players in the squad), and a heading reserves shown (likewise in the team selection email), if not then the full squad will be shown.