asp.net - use appsetting key in mvc view with string -

i trying assign appsetting key value + string in mvc view.

i tried @system.configuration.configurationmanager.appsettings["mykey"].tostring()+"custom/customerprofile.aspx", did not worked.

   <a href="here..." id="donelink" class="btn btn-primary">done</a> 

this how it, assuming want use string in href attribute of link:

@{   var href = system.configuration.configurationmanager.appsettings["mykey"].tostring() + "custom/customerprofile.aspx"; }  <a href="@href" id="donelink" class="btn btn-primary">done</a> 

but, looks not using razor, because link ends in .aspx, not .cshtml. right?