" I just wanted to know if boot disk alone can be used as rescue disk"
I don't know whether the Red Hat boot floppy can be used as a rescue disk without also accessing the CD. As a general rule bootable floppies do not make good rescue systems because they don't have much space. They can only hold a limited number of utility programs. Probably, any useful utilities are located on the CD.
The best bootable floppy system is probably tomsrtbt:
Tom Oehser has done about as good a job as possible in creating a generalized system on a floppy and also cramming in a few utility programs.