nitempany ask the DH to go to immigration to pick up the forms, usually if she's been in HK for a couple of years she will know the process. It's pretty forward if she is a finished contract, financial termination (terminated because the employer lost their job or moved away).
My understanding is though, if she is a terminated contract you need to go through an agency, so no need to ask her to pick up this form, the agency will do all this as they charge a decent fee!