problem with composed types in plpgsql

Hello

I play with new beta version (7.3b2). I trayed compose types created with
create type.

CREATE TYPE tf AS (f1 varchar(10), f2 varchar(10));

I wanted this type as returned type from plpgsql function. But I didn't
find how use this type in plpgsql. When I have function

CREATE OR REPLACE FUNCTION makesettf(integer) RETURNS SETOF tf AS '
DECLARE f tf;
BEGIN
FOR i IN 1..$1 LOOP
f.f1 := ''aaaaa'';
f.f2 := ''bbbbb'';
RETURN NEXT f;
END LOOP;
RETURN;
END;
' LANGUAGE 'plpgsql';

After SELECT * FROM makesettf(10) I got message

psql:testfc.sql:17: WARNING: plpgsql: ERROR during compile of makesettf
near line 6
psql:testfc.sql:17: ERROR: Incorrect argument to RETURN NEXT at or near
"f".

Can I use in this version compose types?
Thank you
Pavel

PS. I can't use compose type in raise parameter too.