The Yahoo LTspice User Group has a freely downloadable LM386 model. Can you switch to LTspice, or perhaps edit the model if necessary to run in Pspice?
Not sure if your asking for them but, generally speaking:
Freq= 1/R x C
For instance, with R=100k and C=100nF, freq=100Hz
Side note: there are quite a few "older" ICs for which there are no SIM models, e.g., the LM386 and one I really wanted, the LM567. Some users have made their own but I just breadboarded them - much easier than trying to create the spice models, at least for me.
The RC formula I gave you sets the frequency of the oscillations, not the shape. A seperate RC (plus the LM386 circuit you choose) confiuration determines the wave shape.
Google "OpAmp" sine, square, sawtooth, etc. wave generator schematics.