Problem with creating TF1 from RooFitResult

I started to working with RooFit and I stuck on one problem. I made RooFFTConvPdf and after fitting I have RooFitResult object and I want to write this fit function, as a TF1 object. I found that it is possible to convert RooAbsReal into TF1 using asTF() function, but I don’t know how connect RooFitReault with RooAbsReal. If someone can help me and show how take out TF1 from RooFitResult.

Thanks, Kasia