This can be set up in Odoo by following these steps:

1. Go to Purchase > Settings and enable Purchase Agreements
2. Go to Purchase > Orders > Purchase Agreements and make sure to modify the Call for Tender according to your needs (exclusive vs. non-exclusive, setting quantities, using lines of agreement).
3. Once the Call for Tender has been modified, open the product template of a purchased item (or export the products) and open the Purchase tab.
4. Under the section "Reordering" select the option "Proposte a call for tenders".

The next time the replenishment for this item is triggered (either by the automated re-ordering rules, the replenishment menu, or a manual replenishment), a call for tender will be created. 

Note: even if there is a single or if there are multiple vendor pricelists set, the call for tender will not pull these vendors into the field "Vendor" nor it will pull them into the RFQs that are created from the purchase agreement. Each vendor will have to be selected manually for each RFQ that is created by users.