self-sign v3

Hi i'm having troubles trying to make a self-sign to use in a public key packet.
I'm using this way :

MD5(0x99(1byte), KEYLEN(2bytes - big endian), KEYDATA, USERID,
SIGNATURE TYPE(0x10 - 1byte), CREATION TIME(4bytes - big endian))

this hash is encrypted using the pubkey i'm exporting and the pkcs1 padding.



Thanks in advance,