fit an erf curve to esf

Hi

I have some data point and am trying to fit an erf (error function)curve to it.

my data is x = [571 600 661 709 757 847 896 1015 1103 1104 1088 1093 1107 1108];

I tried curve fitting but I couldn't get the shape of an erf curve so now am trying to extrapolate the data at the two ends but I was wondering if there is a way to fit the curve directly.

this data represent an edge transfer function.

Thank you Hannah