Permutation function for regression learner

Dear MatLab team

I've trained a regression model with Regression Learner (17 predictors, 20 observations) which gives me a quite good performance (RMSE = 3.5, R-suqared = 0.64). However, I would like to test now the statistical significance of this result. How can I do permutations (permute predictors) ?

many thanks for your help, michael