I am working in a purchase order form with several fields for purchase details, like date, company, provider, among others and a subform with the details of the products to purchase. I have a Product Catalog form, from which I want to bring in some information to the subform. 

so I have this forms:

Purchase order:

date - date

company - text

provider - text

email - email

Subform (in purchase order):

reference - lookup to product catalog

description - text

cost - currency

IVA - number

quantity - number

final cost - currency

Product catalog:

reference - text

description - text

brand - text

IVA - number

I would like that, when the user select an option in the reference the description and IVA fields are filled with the respective product information. And that should happen for every row in the subform. How can I do this?

Any help will be appreciated