This is quite simple. On the left side of designer, you can create new RKF and create like below. Finally you can drag this RKF into KF pane.
Just drag your 0SALES KF into KF pane. Again drag 0FISCWEEK under the above KF and create/use existing variable on FISCWEEK and apply offset -4.
On the other side, you can create a CKF with a formula variable and then use this CKF in a new RKF with additional restrictions. This is for your understanding.
Message was edited by: $um@n Chakravarthy K