http://iscoresports.com/

I am trying to give assisted tackles to players and I can't seem to figure it out.

In iscore you “score what you see” and the program Will then tabulate the stats. So in the play edit screen you have the option to include in a play who made the tackle. Touch the small black icon behind the tackler image to display the tacklers dialog. You can select one or multiple tacklers and you can add new players using the 'Add Player' button.