Here you go Moi
http://www.afl.com.au/Portals/0/afl_docs/Development/umpiring/Laws%20of%20football_2008.pdf5.5 COUNTING OF PLAYERS
5.5.1 request by Captain
The captain or acting captain of a Team may at any time during a Match request that the field Umpire count the number of Players of the opposing Team who are on the Playing Surface.
5.5.2 Procedure
(a) Where a request is made under Law 5.5.1, the field Umpire shall:
(i) stop play at the first available opportunity;
(ii) call into line within the Centre Square the Players of both Teams who are at the time on the Playing Surface and
count the number of Players;
(iii) upon completing the count, ensure that each Team has the permitted number of Players on the Playing Surface and then recommence play at the position on the Playing Surface where the field Umpire stopped play; and
(iv) as soon as practicable after the Match, report to the Controlling Body that a request has been made to count the number of Players in a Team and the number of Players actually counted.
(b) The maximum number of Players permitted on the Playing Surface at the same time is 18 per team or, in circumstances where a Player(s) has been ordered from the Playing Surface under Law 20, 18 less the Player(s) ordered from the Playing Surface.
5.5.3 Players exceeding Permitted Number
Where a Team has more than the permitted number of Players on the Playing Surface, the following shall apply:
(a) a field Umpire shall award a Free Kick to the captain or acting captain of the opposing Team, which shall be taken at the Centre Circle or where play was stopped, whichever is the greater penalty against the offending Team;
(b) a Fifty-Metre Penalty shall then be imposed from the position where the Free Kick was awarded; and
(c) the Team shall lose all points which it has scored in the Match up to the time of the count.
5.5.4 Correct Number and request Without merit
Where a count reveals that the opposing Team has the permitted number of Players on the Playing Surface, the following shall apply:
(a) a field Umpire shall award a Free Kick to the captain or acting captain of the opposing Team, which shall be taken at the Centre Circle or where play was stopped, whichever is the greater penalty against the offending Team;
(b) a Fifty-Metre Penalty shall then be imposed from the position where the Free Kick was awarded; and
(c) if a field Umpire is of the opinion that a request was made under Law 5.5.1 primarily to delay play or such request did not have sufficient merit, the field Umpire shall report the Player who requested the count for Time Wasting under Law 19.2.2.