It's not clear exactly how you intend to use an ' L ' and a ' C ' in a
receiver circuit.
Perhaps you just want a simple resonant 'tank', so that the voltage
across it peaks at 91 MHz. Then you just want to know what parallel
L-C is resonant at 91 MHz.
Without resistance to complicate things, the resonant frequency
of a parallel L-C is
f = 1 / [ 2π √(LC) ].
Before we get tangled up in this thing,
let's just solve it for ' L ' :
Multiply each side by √(LC), then divide each side by f ,
and then it says
√(LC) = 1 / (2π f)
Divide each side by √C :
√L = 1 / 2πf√C
then square each side:
L = 1 / (4 · π² · f² · C)
and now we can easily go ahead and find ' L '.
L = 1 / (4 · π² · 91² · 10¹² · 9 · 10⁻¹²)
When I stuff that through my calculator, I get
L = 0.34 microhenry
