i have the same problem. i need to call a sp in a udf.

this is the function i wrote on your example:

CREATE FUNCTION dbo.c_sel_produs_comF_f

(@furnizor char(14), @data_doc smalldatetime, @tip char(1))

RETURNS TABLE

AS

RETURN

(SELECT * FROM openquery('SERVER', 'exec dbo.c_sel_produs_comF @furnizor, @data_doc, @tip'))

edit: there is something else: OPENQUERY does not accept variables for its arguments