digital signature with CAPICOM

Hi all,
I have a problem .I am using CAPICOM for digitally sign the data and for this purpose i am using SHA1 algorithm.In CPICOM there is one class CAPICOM.SignedData which is used for this purpose.My problem is how can i give SHA1's hashed data to this class (to it's sign method) for returning the digital signature of exactly 172 bit long?
MY CODE.................................
CAPICOM.UtilitiesClass u = new UtilitiesClass();
                CAPICOM.SignedData SignedData = new CAPICOM.SignedDataClass();
                CAPICOM.Signer Signer = new CAPICOM.SignerClass();
                CAPICOM.Attribute TimeAttribute = new CAPICOM.AttributeClass();           &nb ...