Thank you for writing.
Currently, the widths of the columns can only be set by code to a given value. You can use the following code to set the width of the value column:
.radPropertyGrid1.PropertyGridElement.PropertyTableElement.ValueColumnWidth = 80;
The auto sizing for the columns is a good idea and I have added it to our Public Issue Tracking System. You can track its progress and vote for it on the following link - PITS Feature
I have also updated your Telerik points for the good suggestion.
If you have further questions, I would be glad to help.
the Telerik team