I cannot for the life of me, figure out how to add SPICE simulation instructions to a new part. The parts editor seems to have no way to select or edit a SPICE file for a given part, and the documentation, as stated on the website, is currently outdated for the new version.
You can’t add it (AFAIK) via parts editor as it doesn’t support it (prts editor wasn’t completed when development stopped in 2016 and hasn’t yet been completed AFAIK). You need to edit the fzp file and add the splce model. You need to find a spice model for the part from somewhere (be careful of the copyright notices, many are very restrictive of anything but personal use!) and add it to the spice section of the .fzp file for the part like this from the resistor part
<description>A generic resistor (0.25W)</description>
<spice><line>R{instanceTitle} {net connector0} {net connector1} {resistance}</line></spice>
<views>
Connecting the various pins to their Fritzing connector by the connectorId. I believe the only current documentation is examples from parts with spice models (the ones included with the simulator are probably the best bet) or by asking for help here. I don’t think any documentation has been written yet as the simulator is fairly new and not yet complete (and thus work is going in to completing it rather than documentation.)
edit:
Feel free to write and add documentation to the HowTos and Tutorials section of the forums as you figure it out …
Peter
@vanepp is right. Currently, you have to edit the fpz file directly.
We use ngspice for simulation and the ngspice manual can be useful if you do not have a model.
Feel free to ask!