Extension of the basis functions

How do I extract the range of the functions in my basis set? Are this information stored in the .psf file?

The basis functions are generated on the fly based on pseudo-potentials.
.psf files only contain pseudo-potentials and so in there you cannot information about the radial orbitals.

Information about the basis set generate by SIESTA are stored in the .ion files.

However, you can easily get the radial extension of your orbitals by looking at the main SIESTA output file.
The information (in Bohr) can be found in the output file when the basis set are generated and looks like:

SPLIT: PAO cut-off radius determined from an
SPLIT: energy shift= 0.007350 Ry

izeta = 1
lambda = 1.000000
rc = 4.750042
energy = -0.998485
kinetic = 0.898053
potential(screened) = -1.896538
potential(ionic) = -5.447970

izeta = 2
rmatch = 3.475094
splitnorm = 0.150000
energy = -0.862774
kinetic = 1.396939
potential(screened) = -2.259713
potential(ionic) = -6.054640

Alternatively it is also present, always in the output file the PAO.basis block (%block PAO.Basis) in which you can find the radial extension of your orbitals in Bohr.

%block PAO.Basis # Define Basis set
C 2 # Species label, number of l-shells
n=2 0 2 # n, l, Nzeta
4.750 3.475
1.000 1.000
n=2 1 2 P 1 # n, l, Nzeta, Polarization, NzetaPol
5.659 3.653
1.000 1.000
%endblock PAO.Basis