Hello.
I have issue with seam on my prints.
I use slic3r 1.2.9 (tried with 1.3 - same issues occurs).
There is gap before nozzle finish perimeter.

I have delta printer.
Retraction is high (15mm), slicer settings attached.
Anyone can give me an hint what to tweak ?

Do you see the "gap" when you look at the item in Preview mode in Slic3r? If not, it's probably not a Slic3r problem.

You have several printer setup issues there. What type of printer do you have?

I think that you're under-extruding... I don't think there should be gaps between the perimeters of the octagonal part?

Also you're stringing between the perimeter and the items inside the octagon, despite having what seems to me to be a very high retraction amount (15mm). If that's PLA you're printing, I think that your nozzle temperature is too high? 220 is definitely high for the first layer, although 195 is probably good. But try lowering the temperature to see if that helps.

You could also try slowing down your print speed... as a general rule, slower speeds mean more accurate printing.