changing default-face font for specified files

[Luca Baiotti]

 Hi everybody,

                I would like to know how I can set the font-lock to be used 
also for
files with extentions different from the default ones; in particular I
would like to apply to .F90 fortran files the same font-lock used for
.f90 fortran files, which is already set.

Can someone tell me how?

Thanks,

Luca.