Try this:
<RibbonDiffXml>
<CustomActions>
<CustomAction Id="Mscrm.account.form.SendToOtherSystem.CustomAction" Location="Mscrm.Form.account.MainTab.Collaborate.Controls._children" Sequence="33">
<CommandUIDefinition>
<Button Id="Mscrm.account.form.SendToOtherSystem.Button"
LabelText="Check Serviceability"
ToolTipTitle="Sends GPS Data to Spatial"
Command="new_Proj4js"
ToolTipDescription="Sends and Receives Location Data"
TemplateAlias="o1"
Image16by16="new_BillingContact"
Image32by32="$webresource:new_RadioButton" />
</CommandUIDefinition>
</CustomAction>
</CustomActions>
<CommandDefinitions>
<CommandDefinition Id="CMD_JavaScript">
<EnableRules>
<EnableRule Id="Mscrm.Enabled" />
</EnableRules>
<DisplayRules />
<Actions>
<JavaScriptFunction Library="$webresource:new_Proj4js" FunctionName="btnToUTM_OnClick" />
</Actions>
</CommandDefinition>
</CommandDefinitions>
</RibbonDiffXml>