nope rootfs.bin has to be downloaded from Navifirm for your product code,

the name should be DFL61_HARMATTAN_40.2012.21-3_PR_LEGACY_001-OEM1-958_ARM


Edit: Once downloaded just copy it over to in your case e:\program files\nokia\flasher\

For easy operation you might want to rename it to rootfs.bin or just keep it as original there is absolutely no difference...