Hello,
There are two possibilities:
1) ASCII files where zones are defined and the friction of every zone given. See example donau of telemac-2D to have an example. This is not what you started to do.
2) Putting the friction coefficient in the geometry file when building the mesh. In this case the name of the variable must be 'BOTTOM FRICTION ' (32 characters in total) or the same with 'FROTTEMENT '. This variable will be recognised in the file and copied at the right place, i.e. the array CHESTR%R. In this case there is nothing more to do, and the listing will mention that the friction coefficient has been found in the geometry file.
With best regards,
Jean-Michel Hervouet