Give the circuit a couple seconds to begin oscillating.
After some math, the time to charge/discharge the cap is:
t = 0.69315*R*C
T = 2*t = 1/F, Let F = 100kHz
2*t = 1/100kHz ==> t = 5uSec
R*C = t/0.69315 = (5uSec)/0.69315 = 7.213uSec, Let R = 1kOhm ==> C = (7.213uSec)/(1kOhm) = 7.213nF ~= 6800pF (close standard size)
