I've renamed two roms from .bin to .smc and neither are displayed on the SD2SNES menu. They have both been copied to the roms folder.
Did you try renaming to .sfc?
.smc is a sort of outdated extension.
Also I would imagine SD2SNES would not want another headers (headers are another thing that is outdated, a header is 512 extra bytes of garbage that is probably only meaningful to really old floppy-disk era devices.)
A good Super Mario World ROM without header is exactly 524,288 bytes. I think Addams Family is a 1,048,576-byte game.