Help! Modification of Floor Support

[Dongray]

Hey Guys, I have installed a new passenger floor panel and am ready to install the floor support. When I position it the end of the floor support nearest the rocker panel doesn't seat very well. It has a step in it (see picture) that is intended to accommodate the rocker panel but it is too short and rides up on the panel.
Does anyone have suggestions on how to move the step in the floor support about a 1/4 inch? Im not a metal worker so this is all new to me. Thanks!