Combine rice, almonds, currants and orange rind in a bowl. Heat the rice syrup gently in a saucepan over low heat until warm then pour over rice mixture. Stir well.
Line a small rectangular baking tray with baking paper. Spoon mixture onto tray, then flatten firmly using an additional piece of baking paper. Refrigerate while you are preparing the chocolate.
Melt chocolate gently in a bowl placed over boiling water. When melted spread the chocolate over the biscuit base. Refrigerate until cold then cut into squares.
Note: To bind the ingredients together better, spread the chocolate completely over the biscuit.