Return Single Row Result After Inserting (Stored Procedure)

Hello all,

I have the following procedure. I wish it will return a single row result to caller, after I insert the value (as the
rowcontains several auto generated fields), without perform additional SELECT query. 

According to http://wischner.blogspot.com/2009/03/creating-stored-procedure-function.html, my guess is that, I need to
useSETOF. However, pgAdmin doesn't allow me to enter "SETOF" in "Return Type". 

However, it let me enter "lot" (lot is the name of the table)

May I know how can I modified the following function, to let it returns my newly inserted row?

CREATE OR REPLACE FUNCTION create_lot(text, text, text, text, text, text)
  RETURNS lot AS
$BODY$DECLARE
    configurationFile ALIAS FOR $1;
    operatorName ALIAS FOR $2;
    machineName ALIAS FOR $3;
BEGIN
    INSERT INTO lot(configuration_file, operator_name, machine_name)
    VALUES(configurationFile, operatorName, machineName);
END;$BODY$
  LANGUAGE 'plpgsql' VOLATILE
  COST 100;
ALTER FUNCTION create_lot(text, text, text) OWNER TO postgres;

Thanks and Regards
Yan Cheng CHEOK

p/s May I know what is the purpose of "COST 100"?