using Bjontegaard metric in k-means clustering as a cost function

Hello,

I am trying to use Bjontegaard metric as cost fucntion in kmeans. I have some RD curve and I want to cluster them based on their slop. this means vectors that are near to each other and has near slop put in same cluster. for this I want to use Bjontegaard metric but I do not know how can I replace the cost functions with this? could you please help me how can I do this? A Matlab cod for Bjontegaard metric is also in this link:

https://www.mathworks.com/matlabcentral/fileexchange/27798-bjontegaard-metric

Thank you.