I have just recently taken a job at a company primarily doing RF
designs. I won't ask anything ridiculous like "How do I design for RF?"
but I have two simple questions:

In the past I have always called out "Soldercoat all exposed copper..."
on the fab dwg, but here they are using tin plating. What is the
difference between tin plate and soldercoat?

Many of the RF designs here were done in AutoCAD, and the only reason I
have been given for this was that it was easier to chamfer the corners
of the delay lines (fairly wide 50 ohm traces on 20mil teflon). I may be
wrongly assuming that the reason for the chamfer was to minimize the
effect of the impedance change "around the corner", but my new CAD
package can do curved traces which suggests NO mismatch around bends...
constant width everywhere, right? 
Unfortunately, no one here has any data to support the need for
chamfers. (I have to painstakingly enter precise polygons if chamfers
are really required, so I would rather avoid it). 
We are working with 1.9GHz, and are moving to Rogers 4003 material.

Can anyone with RF experience comment on this? 

in the dark....				     jack, the new guy

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