How do I create an exponential model for 6 x values?

[#1]

I am trying to develop an exponential model of the form y=a(x1)^b + c(x2)^d ... for a set of 6 x values and 1 y value. I have read that this should be possible on JMP 16 using the fit model function. I have tried fit model and am supposed to see "custom model" or something similar under the personality drop down menu and do not see this. If anyone knows where I would be able to choose an exponential model or create one that would be appreciated. Attaching a photo of what I see under "personality"

[#2]

Fit Model leads to many personalities to fit linear models. Your case is a nonlinear model. See the chapter about the Nonlinear platform in the JMP documentation. You might be able to use the Fit Curve platform instead.

[#3]

I am not able to add more than 1 x value to the fit curve platform. 

[#4]

I should not have suggested Fit Curve since you cleary referred to 6 predictors. Follow the instructions for the Nonlinear platform. Pay particular attention to the section about custom models. You will create a column formula for the model.