Try this, you'll have to run 'make' in /sys/dev/usb after applying the patch then build a kernel as usual.
Index: usbdevs =================================================================== RCS file: /cvs/src/sys/dev/usb/usbdevs,v retrieving revision 1.605 diff -u -p -r1.605 usbdevs --- usbdevs 5 Sep 2013 19:42:09 -0000 1.605 +++ usbdevs 29 Sep 2013 01:14:48 -0000 @@ -1124,6 +1124,7 @@ product BELKIN F6C800 0x0980 F6C800 UPS product BELKIN RTL8192CU_2 0x1004 RTL8192CU product BELKIN F6C1100 0x1100 F6C1100/1200 UPS product BELKIN RTL8188CU 0x1102 RTL8188CU +product BELKIN RTL8188CUS 0x11f2 RTL8188CUS product BELKIN F5U120 0x1203 F5U120-PC Hub product BELKIN RTL8192CU 0x2102 RTL8192CU product BELKIN F7D2102 0x2103 F7D2102 Index: if_urtwn.c =================================================================== RCS file: /cvs/src/sys/dev/usb/if_urtwn.c,v retrieving revision 1.30 diff -u -p -r1.30 if_urtwn.c --- if_urtwn.c 20 Aug 2013 04:52:00 -0000 1.30 +++ if_urtwn.c 29 Sep 2013 01:15:18 -0000 @@ -86,6 +86,7 @@ static const struct usb_devno urtwn_devs { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_F7D2102 }, { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_F9L1004V1 }, { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_RTL8188CU }, + { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_RTL8188CUS }, { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_RTL8192CU }, { USB_VENDOR_BELKIN, USB_PRODUCT_BELKIN_RTL8192CU_2 }, { USB_VENDOR_CHICONY, USB_PRODUCT_CHICONY_RTL8188CUS_1 },