When you do this, the standard File Chooser dialog appears, as shown below.

To import a thermistor curve file, navigate to the xml folder in the kitIo module (Jar) file in your modules (My Modules). Or, navigate to any other location you have a thermistor curve file. Import any other saved, custom non-linear conversion .xml files the same way.
As of the date of this document, the kitIo module contains an xml folder with five (5) different thermistor curves in xml format, as follows:
Upon any curve file import, all existing thermistor or non-linear curve configuration for that Nrio point is overwritten (replaced by configuration in the imported file). A confirmation dialog advises you of this before you import.

To export a curve .xml file, use the File Chooser to navigate to any location you wish to save the current thermistor or non-linear curve configuration, and supply a File Name. You can use this saved .xml file in the configuration of any other like Nrio proxy point, whether in this station or another station.