<p>I started using rafts more often, to get better results with complex or fragile parts, but my Ender 3 consistently under-extrudes the initial outside line of the raft (for the first inch or two, where extrusion starts). </p>

<p>It is often very thin and does not adhere. This often leads to problems with the following pattern of raft layer 1 curling up (ABS) as it does not meet the edge line (due to the 1-2 inch gap in the perimeter).</p>

<p>Skirts avoid this problem by getting the flow going, but rafts only print a single outer line.</p>

<ol>
<li>Is it possible to specify more than one outer line on a raft in Ultimaker Cura?</li>
<li>Is it possible to add a skirt to a print that has a raft (or at least some initial printing to get the flow going)?</li>
<li>Is it possible to add some initial G-code that will extrude a line, say from near the start position to the start of the print?</li>
</ol>

<p><img src="https://i.stack.imgur.com/zqaay.jpg" alt="example of problem"></p>

It's not necessarily the case that the apparent underextrusion of a small portion of your raft is the root cause.  ABS is notorious for shrinkage and peeling.  As a start, you should have a full enclosure so as to maintain a warm environment while printing.
It's also quite possible that your bed is slightly off-level or a few microns low for the first layer, either of which can cause adhesion problems.
Yes, it's pretty much trivial to add a few lines of gcode to extrude prior to the "official" raft -- or you could just toss a fake small object into your slicer to extend the raft over both the real and the fake parts.
FWIW, with a little care I've found a wide brim outperforms a raft for almost anything I print