I am looking to apply a certain type of vegetation to a model; is there a way for me to be able to create a custom ecosystem, or is there a way for me to create my own .nrp file for importing into RN?
mvandermate Yes, of course. Please refer to https://help.rhinonature.com/getting-started to start with your own ecosystem with desired models. After that hit the Save button in Ecosystems rollout. You'll see a popup that allows you to select ecosystems you want to save. Select them and proceed. Now you'll see https://help.rhinonature.com/manual/library-browser/preset-information where you can specify a name, thumbnail etc. and select that you want to export models used within the ecosystem. RN will handle all exporting into separate 3dm files for you.
If you want to learn the in-depth structure of presets you can check (in installation folder > App ) you'll find a detailed description of the preset xml scheme.