The K-Means button is found on the toolbar and under Outlier Detection.

• Number of Clusters: The number of clusters to be calculated.
• Maximum iterations: How many times the calculations will be run, more iterations will refine the results at the cost of longer processing times.
• Run Cumulative Variance Model: Can be used to determine the range of the K-Means test using variance explained instead of number of PCs
• Number of PCs (1-25): The number of principal components representing the workspace.
• Scale PC Scores to Variance Explained: Normalizes the scale on the workspace scores using the variance explained
• Use Custom Seed For First Centroid: Allows the selection of a custom seed instead of a randomly generated one, creates consistent results across runs.

A more in depth guide on the uses of K-Means and how to run one can be found here.