I know the question is pretty old, but in case someone needs a working solution:
RelativeLayout.LayoutParams lps = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
// This aligns button to the bottom left side of screen
lps.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
lps.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
// Set margins to the button, we add 16dp margins here
int margin = ((Number) (getResources().getDisplayMetrics().density * 16)).intValue();
lps.setMargins(margin, margin, margin, margin);
ViewTarget target = new ViewTarget(R.id.buttonBlocked, this);
sv = new ShowcaseView.Builder(this)
.withMaterialShowcase()
.setTarget(target)
.setContentTitle(R.string.showcase_main_title)
.setContentText(R.string.showcase_main_message)
.build();
// Set declared button position to ShowcaseView
sv.setButtonPosition(lps);
This worked for me, hope it helps somebody.