If for some reason that is not sufficient, then use the following code to produce the plot by using PROC G3D. Note that I've used a grid that is more balanced than yours in terms of the X and Y locations of the grid points:
P_DTTAO = . ;
do Time = 0 to 12;
do Dose= 0 to 16 by .1;
set rsm rsm2;
proc rsreg data=rsm2 out=predict noprint;
model P_DTTAO=Dose Time/ predict;
proc g3d data=predict;
plot Time*Dose=P_DTTAO / rotate=38 tilt=75 xticknum=6 yticknum=4
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