Hi Frank, a simple example worked for me. How do you get the error?
In[1]:= returnList[i_] := {i, 2 i, 3 i}
In[2]:= t3 =
Compile[{{x, _Real}, {k, _Integer}},
x returnList[k], {{returnList[_], _Integer, 1}}];
In[3]:= t3[2.3, 2]
Out[3]= {4.6, 9.2, 13.8}