Here is my take on this: (without looking at the link page)
C2 should be about 47pF (not critical) at the upper end, and around 68pF -100pF at the lower end.
R3 x C3 = 0.5/F (Make R3 variable during tests, take precaution for R3=0! by inserting safe fixed value in serie)
Where R(ohms), C(uF), F(MHz)
C1 and L1 will be series resonant at the required frequency using the basic formula Fr = 1/2*Pi*SQRT(L*C)
Making C1 smaller will raise the frequency. Making L1 bigger will introduce some more phase-lag an lower the freguency.
You have to choose your values close enough cause you will only be able to "pull" the crystal frequency by a couple of hundred Hertz
R4, in most cases can be left out