See the follow the below instructions to create a Rate Based Blanket PO:
To create a new blanket order, click on Blanket from the New Order menu on the landing page.
Select the 'Rate-Based' option under Blanket Options.
Click on + Add item to add an item. You need at least one line to create a blanket purchase order.
Let's assume if someone charges £50/h for work and you want to create a PO for 0.5 hours then enter the required figure in the 'Rate' field.
After filling in the other details, click on Submit if you want to submit the order.