Uploading a CSV file in UserIQ.
You must already have the CSV file created, see here for information on creating a CSV.
Click your name in the upper right corner of the menu bar and click Site Settings.
On the menu to the left click CSV File Management
Click Upload New File
Provide a name for the file
Locate the file to upload
Select the file
Click Save Column Values at the bottom of the page once the content appears
Now the file will be available under the Audience and Segment filter User Attribute in Uploaded CSV
Please note that you would have to use a single column CSV (all values in one column) to successfully use it in the segments as audience filters. Displayed below is an example of a list of user_id's in a single column.