It is 100% possible out of the box!
On your Item card (or SKU if using Locations), set the Reordering Policy to either Order (1:1 with forced reservation) or Lot-for-Lot (Many:1 with optional reservations). With either of these options set the system will start making recommendations to purchase the Item based on Job demand.
If you want the Job No. specified on the PO, you have to use the Order policy. This creates a reservation, so you have to make sure you're warehouse staff is disciplined on receiving and staging the Items for the Job specified.
If you are okay without the Job No., but knowing the system is planning the supply, use Lot-for-Lot policy. This avoids the potential headaches associated with reservations.
Reach out to your partner for additional information on how to fine tune these settings to get the Req. Worksheet giving you the best results for your business.
(Edit) P.S. Make sure the "Apply Usage Link" is checked on the Job. You can set this default to on in the Jobs Setup
